Re: App gap
There is one serious app gap where Apple just trounce the competition, and that's music-making. For better or worse, iOS is the platform of choice for serious music devs. If you're a musician, then iOS is simply streets ahead of both WP and Android. That's a fairly small niche market, though. And, honestly, for such things interface size matters, so it makes much more sense to get an iPad for your music-making than to use your phone. And so this is one area where Microsoft are competing: allowing any Windows app to be installed on a Surface makes it a very serious music machine without their having to spend time persuading devs to recode all their stuff for a new OS. That being said, if they could get Ableton or Steinberg or someone to build a version of their DAW or even just a decent VST plugin host that runs on RT, that would be a game-changer.
The other gap is a decent cloud music player. Amazon have supposedly been working on their Cloud Player for WP for two years now, but still no sign of it. You'd think someone would have built a decent music player for playing stuff off your Onedrive by now, but nope. Style Jukebox (terrible name) is the best I've found, but it's not great. If someone has their entire music collection in Amazon's cloud (or any cloud), I can see why that might be a good reason not to buy WP, for now. Mind you, I do, and I still reckon WP's pros outweight the cons.
There is also an extremely good carb-counting app for diabetics on iOS. Again, a smallish niche market. There are some pretty good ones on WP as well, but the best (sorry, I forget its name) is on iOS. That being said, my diabetic wife got an iPhone just for that app and hated the damn thing so switched to WP. She keeps the iPhone around just for that one app but didn't think it was worth putting up with the shitty interface in every other aspect of her phone use.
That pisses me off, actually. The "We have an app for your iPhone!" craze is all very well, but, if you're a healthcare company, surely it's your job to make your product as available as possible, not to choose a single platform and ask users to accommodate you. The very idea of providing a useful healthcare app for iOS users only is pretty disgusting, in my opinion.
Those things aside, yes, most of the complaints seem to boil down not to people wanting an app that does a particular thing, but to wanting a particular app no matter how many alternatives there might be that do the same thing. Creatures of habit.