I think it's fairly safe to say that the show, while obviously popular due to the talent that is on display through the contestants, that there is also a strong comedic element as well, and that comedic element would seem to be strongest in the comments made by Simon. Rumor is that he will not be returning for the 10th season, if a 10th season will even be in the cards (which I think it just might), and so it would seem fairly logical to me that they would want to install somebody who can be humorous (whether or not we ultimately agree on either her brand of humor or Simon's is not at issue necessarily) but who can also relate to public scrutiny for reason beyond simple raw talent.
I'm not sure she's the best choice yet. But I do think it's also too early to call her into judgement. Let's give her a shot and see what she can do. If the powers that be see problems and believe she is the cause, they'll be very quick to make some changes.