Earlier quoted context omitted.
We probably have a different view on what is a killer app. From my perspective: Windows - Outlook Express, IE. OS X - Mail, Safari. I can't recall the last time I fired up "Photoshop, Excel, Quicken, Final Cut" and I bet 90% of randomly selected users couldn't either.
Maybe this theoretical question. If you polled a random user of, what are the chances you would find an app that they will get very pissed off at it's disappearance? What are the chances they will actually skip platforms? On Windows or OSX, I think the answer is high. On iphone, maybe not.
It is still a luxury for most people - "oh cool look at this app," but it still comes down to those that can afford an iPhone. I can imagine there are many family squabbles involving parents that bought their kid an iPhone that racked up an App Store bill the parents didn't originally intend.
iPhone is not a business phone overall - and therefore doesn't have "critical apps".