I hear you, and I am of two minds on the subject. As a user, I'd want a single unified store (iTunes) to get everything from since it's the easiest, quickest, cleanest way to deal with the process.
However, as a developer I am realizing more and more that more stores equals MUCH more chance for exposure to my product. I've done my time on iTunes, and dealing with Apple (for better or worse) is truly a crapshoot for a tiny guy like me. The odds that I can potentially get some actual feature/promotion when I am dealing with a lot more of these smaller/middling stores is far more comforting, as to be honest it really is the hardest part of the whole process.
Anyway, I'll always do my best to have my apps available on the highest-visibility store (and I'd suspect many devs at my level would feel the same) so that if people actually do know me, they'll not have so much of an issue finding my work. In the case like Cut the Rope, which is a fairly high-profile game, I am extremely curious to know the politics involved in it's seemingly exclusive appearance on GetJar.
EDIT: I'll assume it means they can keep more money, and build up their own store to sell other products down the road (publicizing not only their game's brand, but their store's brand as well)
