It’s not the customized apps themselves that are (to my eyes) ugly – though that may sometimes be the case – it’s the inconsistencies, the lack of polish and the lack of thought that usually comes with having a customized UI.
Sure, but my point is that buyers don't know whether the UI is consistent or not until they actually buy it. All they have to go off of are screenshots, and if they see screenshots of standard looking SDK components they'll gloss right over it. The app store is essentially window shopping, that's why overdesigning sells. So given a choice between pleasing UI snobs and actually making money, it's not a tough decision to make =)
EDIT: Re trials: most paid apps (mine included) have limited free versions that you can try.
