I think the thing with Cena was to show that the draft is really random and 'anything can happen' etc. You know, "oh, Smackdown thought they had bagged Cena but no!", that sort of thing. The shows don't get to choose who they draft....
The Tag Team Champions can appear on both shows so I assume that Show and Kane will just appear together on both Raw and Smackdown until they lose them.
The word on Sin Cara is that they moved him to Smackdown so they can edit his matches, as he's made a few botches recently. So no, I don't think they do think he's ready to be a big star yet.
I don't think it "sucked balls", my biggest issue is that it seems like a ton of guys who used to be on Raw are now on Smackdown and vice versa (after the supplemental draft at least).
I don't think ending the brand split would necessarily do any good, because a lot of guys would then just be shunted down the card or even released if WWE can't fit them all onto their shows....