Except there really AREN'T thousands "key apps," anymore. Almost every meaningful experience is on the platform now. Candy Crush (which, as I have said, is Bejeweled), is probably the BIGGEST name with no presence on Windows Phone, outside of the suite of Google applications (which is due to Google's crappy business practices). We have third-party experiences for most of the applications people want, and even though they are third-party applications, they are high-quality ones that can be enjoyed. We're at the point where GameLoft is talking of simultaneously releasing games with iOS and Android.
Really, Candy Crush isn't a major loss. Are you saying that Candy Crush alone is enough to make you wish you got an iPhone, or is there other stuff you are missing that you just don't feel like mentioning? You can say that you feel like you're missing out on stuff on Windows Phone, but I feel like I would miss out on a lot MORE if I left for Android (I wouldn't touch iOS with a 700-foot pole, Apple is a disgraceful company). No, I didn't have to try hard to find Trillian. Heck, I didn't even really use it much on Android, nor do I use IM+ much on Windows Phone. The two offer the same services, almost 100%, so it's not like I am losing out on ANYTHING going from Trillian to IM+. I don't lose compatibility with services or anything, and that's my point. You can experience just about everything on Windows Phone, and the stuff that you can't experience, I can't even name.