[makecheck]

This isn't just in mobile apps, it happens on the desktop too; and it's a tricky problem. In general one has to blow up the size of an app to preserve a good user experience in other areas.

Consider download complexity. How many "versions" of your app would you need to have to give each user the optimal installation size? How often do you want to deal with people downloading the wrong one and having a bad experience? What about 3rd party distribution...any number of other sites may choose to offer download links and you have basically no control if they screw something up.

Another is problematic upgrades. Suppose you optimize a download for a user's current machine. Then they buy a new machine. They won't really try to understand why your app is now looking strange or misbehaving; they'll just think your app sucks.

On the Mac side I've chosen to go the oversized route. There's no doubt that my app bundle is 2-3 times as big as it ought to be (and unfortunately two thirds of the binary bloat goes towards supporting systems that few users are likely to care about at this point). But then downloads are simple: just "click here for the new version" and whatever your system you see something that works.