I've lived in Singapore all my life save for a few years in the US.
This article's points are weakly argued, and Singapore's staidness is entirely a first-world problem which people from some neighbouring countries wouldn't find much of a problem at all. But on the whole, I'd agree with the author that Singapore is lacking in quite a few ways compared to the top cities (economically or culturally) of the world. Off the top of my head:
1) A conservative, risk-averse, wealth-focused culture of keeping up with the Joneses. This is mostly the modern result of traditional Chinese competitiveness and desire for 'face'. Parents live for their children - you want your kids to do well so you can proudly tell others about them, and because you expect to support you financially when you're old. You pressure them to take the well-respected and profitable route in life, and you prohibit them from taking the risky path to inevitable ruin as a starving artist, etc.
The children then go into executive jobs, trying to be managers, avoiding the low-paid engineering/technical positions (programming, pfft, that's for cheap foreign labour), and not caring very much about things that don't have an immediate impact on their careers or everyday lives. The endgame is to own property and collect rent, which is the main gateway to wealth (as it is in most of Asia - just look at how the majority of Asian tycoons made their fortunes).
This causes most Singaporeans to be relatively homogeneous in the things they do and their outlook on the world. You won't find anywhere near the range of activities, passions and hobbies that Americans engage in. Everyone does the same few things, and talks about the same few topics, all of the time.
2) A dearth of dreams, imagination, and world-changing idealism. The core value of Singapore is pragmatism, and it's built into every facet of this place. The parenting, school system, government, and even national service in the military all shape citizens toward a very stable and staid pattern of thought: that things can't be changed, that responsibilities to family come first, that there's no point trying to correct the system or working to change it because the school/army/corporate/government bureaucracy is too entrenched and won't ever listen. This sense of "nothing's going to change, why bother fighting" was particularly bad in the '90s and before, and I still hear such opinions from my parents. Is it a surprise, then, that innovation wasn't too prized until recently?
It doesn't help that there didn't use to be a wide range of employment available in the earlier decades, so not many people tried to eke out careers in more unusual areas, much less start campaigns to change Singaporean society and the world. The older generation of Singaporeans would deride these endeavours as mere dreams and silly teenage notions; you'd grow out of it eventually and become a doctor or executive or whatever. Hardly anyone has made a big impact internationally - whether as an athlete, artist, scientist, or entrepreneur - which meant that there were few role models for kids to look up to. No Michael Jordans or Bill Gateses here.
3) Size. Many of Singapore's problems stem from its size. The lack of space results in runaway rents. Sky-high rents drive out less profitable business and ensure few people can experiment with new, risky concepts that don't turn a big profit. This keeps businesses more conservative and makes it hard for organic enclaves to emerge here. (You rarely see unoccupied shop space here, much less abandoned buildings where someone might throw a pop-up party or hold an exhibition.)
High rents also mean everyone lives with their parents, can't afford to buy a house till they get married, and is reluctant to rent a place. They don't have their own space to socialise, have people over, live their own lives, which makes for a pretty sober existence - literally and figuratively. (I suspect this is one reason the rate of singlehood is really high; we simply don't have enough fun with friends, and rarely meet new people.) Then the high density also leads to massive peak load on public transport, which worsen the daily experience.
The island's small size and heavy urbanisation leaves it with few natural scenic spots. You have to fly out to get anywhere scenic (this is related to point 4).
Finally, the small population isn't a very attractive target for entrepreneurs, and the lack of a shared culture with nearby countries makes it hard to penetrate those markets without moving there. It also makes it a much more comfortable bet to be a professional than an entrepreneur or artist. Having few successful entrepreneurs leads to fewer kids having big dreams.
4) Climate and geography. The heat and humidity mean that it's simply not enjoyable to hang out in the sun. You can't enjoy long walks or bicycle rides here without getting drenched in sweat. If you hang out with friends, you do it in air-conditioning, which means restaurants, bars, and shopping malls. I can't go and sit on the grass like I did in the US, much less head out of town to snowboard, walk through vineyards, or camp by a lake.
It's also a relatively flat island. An American friend's visiting mother remarked that one problem with Singapore is that it lacks a mountain, and she's right. Add to that the lack of seasons and the relatively monotonous tropical foliage, and you end up with nature that isn't all that enjoyable and barely any scenic vistas. In stark contrast are the natural and man-made sights of Japan and Taiwan, which awe Singaporeans endlessly - it's no surprise that they're probably the most popular travel destinations for us.
5) A lack of natural community and social openness. Like many dense cities, we don't have many events and local festivals that naturally bring communities together. This is in contrast to the festivals that occur in many neighbouring countries, in Europe, in Japan, and wherever old traditions have been preserved. Many Singaporeans are strangers to their neighbours, which makes for a small social circle and a closedness to making new friends outside of school.
There's no culture of talking to strangers at all, and children are actively discouraged from taking an interest in other people (being a "kaypoh" busybody). I remember this acutely from my own upbringing; you minded your own business, because you'd probably look silly if you tried to interfere in others, or even get in trouble.
A co-worker from Vietnam commented that while he makes much more money here, he finds that home offers more enjoyment and celebration of life and friendships, more things to do, and less of a focus on work and earning money. This echoes comments I've heard from foreigners from France, New York, China, and elsewhere.
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Some of these things have changed a bit, especially with the changing outlook of top politicians, the livening up of the city centre, and the loosening of old bureaucratic rules. Many more people have travelled or lived overseas, which has lead some to import foreign ideas: witness the boom in cafes, bars, campaigns and organisations started by yuppies who fell in love with an idea, a style, or a culture while they were abroad. But the historical inertia of being a pragmatic, competitive, unidealistic, and unopen culture is too much to overcome in a mere decade or two.
No magic ever happens in Singapore. Godzilla attacks Tokyo, mobsters run Hong Kong, down-and-out writers shoot to fame in New York, Hollywood stars zip around Los Angeles, tech revolutions start in Silicon Valley - but Singaporeans would scoff and laugh at a movie that set the fantastical or whimsical in Singapore. We're enraptured by the fairytale fantasies that Korean dramas spin, because we have none of that. We can't imagine anything interrupting our routine, everyday lives and stolid bureaucracy. It's like being in a small town and knowing that monsters will only ever attack New York. That's the upshot of a Singaporean upbringing.
I completely understand why people would leave for more culturally rich places. I hope to eventually spend at least half my time out of the country, probably through building a cross-national business - but for now I'm stuck here, looking for the right connections and opportunities (if you're in town and have a good idea, get in touch).