Something I think about a lot is what the world would look like without advertising, i.e., you'd have to make every decision on its merits, and never rely on bought opinions. Like imagine you walk into a grocery store, and every shelf is lined with plain cardboard boxes with the name of the product on it ("chocolate-covered breakfast cereal") and a nutrition label. You walk in and there is nothing other than the merits of the product itself to guide your purchasing decision. Nothing else would influence you.
Would that world be better than today's explosion of colors and brands and talking heads and size 100 font "NEW FORMULA!!!"? In today's world, if you're not sure what to buy, you just pick the thing with the most colorful box or whatever you heard about on TV, and you probably end up with something that's fine. (Occasionally, the thing you heard about on TV is actually good, and you wouldn't have thought to buy it otherwise. It's almost a win-win though I am somewhat hesitant to use that term to describe advertising on HN ;)
Advertising is that; you don't care what brand of light switch you buy, you just want a light switch, so there is a race to convince someone you trust to recommend their brand to you. They pay someone money, you buy a light switch, it switches your lights, you're happy, they're happy, and this random third party ad company is happy. Multiple people are bidding against each other for this recommendation, and so advertising ends up costing a lot. (You, of course, pay the cost, not the company doing the advertising. But if everyone is doing it, it's not like you can choose.)
That's the app store thing; Apple prides itself on how every iPhone app is the greatest thing ever created, and because sometimes that's true, you trust them. Well, what if they just approve everything and let people pay for recommendations? Now you have ads in the app store. Someone looking for a random app gets a random app. They're probably happy with their $0.99 purchase. They never think about it again and move on with their life, and Apple's execs get a cooler yacht, and some random software engineer also got 10 cents or whatever. This all seems a little wrong -- ideas and products should only be popular because of their merit in the global marketplace of ideas -- but is it actually? It's really just making a lot of money from making decisions that aren't worth making.
It does sound really dystopian... don't think about anything, just CONSUME what we say to consume... but is researching light switches so that the true best light switch maker gets your money actually better than spending an hour playing with your dog or whatever? I don't know. It's difficult. I should think about it less.