Of course it doesn't, because of many reasons, some of which are

a) the SDK approach allows you to develop software even if you are a Mac or Windows developer (or, say, don't know anything about Debian)

b) it also allows easier target switching, on device development will not net you simulator, MeeGo Handset or Tablet, Symbian, Maemo5, etc targets

c) the average computer used for development is still equipped with way faster CPUs and more memory making it a lot faster to cross-compile or to do separate targets or different versions of them.

d) I'm pretty sure more people would appreciate work put into a mail client or web browser than catering for a very thin use-case

e) if you're a cool hacker, you can do it on your own anyway, and it's a billion times easier than on any other platform

f) need I go on ?

So yes, it would be worth some geek creds with a few dozen people and be an annoyance/hindrance to millions. That's an easy call to make.