They don't want people jailbreaking so if they simply added "themes" they could probably eliminate 80%+ of the JB'ers as well as sell themes for 99c each and make some (more) money). I really thought that was going to be a feature of 4.x.
Yea, but there's plenty of "UGLY APPS" cluttering it already so what's the difference? Probably 50% of the APPS are useless drivel and 30% are just plain useless which equals 80%. The market will bear it out.
Not sure that it'll make as high as 80% jailbreaker to give up JB. I personally hate theme and don't use it. I much prefer iPhone stock appearance. I jailbreak for stuffs like sbsettings, quickscroll2, download manager, mywi, unrestrictor, full preview, ifile, etc. Theme was never one of my reasons. I have a feeling that it may only eliminate just 5% of the jailbreak but I could be wrong.
I honestly think Apple doesn't care about people who jailbreak for the customisation aspect of it but is a lot more worried about people running illegal apps. As long as the cracking community is crackin' the jailbreaks will be frowned upon and Apple misses out on its share of the revenue streams.
I personally JB for things like unrestrictor, ua faker, sbsettings and volume button extenders. I messed with winterboard and theming and grew tired of it. Sometimes less is more for me. Just my opinion.