It's been said that the only reason Nikki Bella won the Diva's Championship was because WWE doesn't want Kharma to defeat Beth Phoenix for it and presumably ruin the payoff that will come from having a feud between the two with Kharma as the dominant champion and Phoenix as the face looking to pull off an upset, or something like that. In any case, it's pretty insulting to Nikki to blatantly portray her as a transitional champion if these rumours are true.
I'm very happy with how Brock Lesnar's character is coming across. I did say when news first broke of his return that I thought it would be wrong to portray him as a face from the onset and this opinion still stands. Lesnar is one of those perfomers that people loathe, but love at the same time because his skill as an athlete is phenomenal and he has a wide understanding of in-ring psychology. Sure, he's no CM Punk on the mic, but this doesn't necessarily factor into his character and he provokes an intense reaction by just being arrogant.
Lesnar's a guy that has been very successful at nearly everything that he's done. He may not have made it into the NFL, but he still made it to the trials and although I'm no expert on American Football, I'm sure that's a pretty big achievement in itself. His character's arrogance is justified, because he's actually every bit as good as he says.