If you are going to put out a new software program, what platform are you going to target? The one that can make you the most money. If you are going to have to build an app from scratch, you are going to target the platform that your potential users are using. Nobody is targeting Blackberry anymore. Or Palm. Noone builds apps for Symbian despite the fact that they have more than twice the marketshare of Microsoft in mobile. You look at your target market: Apple and Droid own more than 80% of the market and are pretty evenly split.

Noone goes fishing for the smallest fish in the pond.