"Here download my free minesweeper game." (Game app secretly uploads the user's phone number and/or contact list to a server in Russia in the background.)
The only, sanctioned, applications will be available via the app catalog which go through a review. Even if Palm misses this, others won't and it'll get pulled real quick.
Besides, you can already access the entire contact list so what does it matter if one more number is exposed?
I really can't imagine the user who can't handle simply typing in their phone number to subscribe to a service, considering that that's what they already have to do on every desktop web service that uses SMS notification.
Erm, no one said they couldn't but it provides a bad user experience. The less input they have to do the better especially on a phone that should already know its own phone number