New graphics on the new iPad 3's screen look amazing. But they really do make the apps much bigger. Individual images can be up to 6MB! (Like in this app, where we want image quality the best, no matter the size.)
It makes a difficult choice, especially for Universal apps that run on both iPhone and iPad. For a long time the limit for an App to be downloaded over the cell connection was 20MB. The iOS 5.1 update did increase that to 50MB.
But since it's done by the iOS version on the device and not the App Store server, anyone who hasn't upgraded still has the 20MB limit. People upgrade pretty well, but looking at some stats, it's likely that half of the people still haven't upgraded to 5.1 yet.
Even if the people are upgrading from 5.0x to 5.1 quickly, that 20% on iOS 4 are upgrading very slowly. At this point many months after 5.0 was released, I doubt they really are "upgrading." They're getting upgraded as they buy a new device.
I don't want to throw away between 20 and 50% of potential customers, especially on some sillier apps like Knife Dancing that are downloaded quite often while out and on a cell connection...most likely there are drinks involved too. Same for Pawn'd, we're putting in the iPad Retina graphics and it looks amazing, but it will push it way over the 20MB limit for older devices to get with a cell connection.
We're trying a hybrid approach for some apps. Upgrading buttons and things that contain text because the small curves with high contrast in text show the most pixelation when not upgraded. But leaving some other things alone for now. (We did that for Knife Dancing, plus some tricks Pete did with double images, coming in at a bit under 20MB.)
We're seriously thinking of making the planned free version of Pawn'd be iPhone only to keep the size down, and maybe a separate HD version for iPad...or just add the Universal part in a few months when more people have upgraded.