^ Pretty much agree with this. When I was a kid, I adored birds, so naturally I objected to them 'abusing' him... but, of course, I've come to realize he's mostly there for comic relief, and I don't feel like he has a lot of screen-time in the movies. He plays a relatively minor role, so in a lot of ways he just kind of slips under my radar a bit. I don't have any strong feelings for him one way or the other.
That said, I've never really seen people 'hate' on Zazu. What you've cited so far I wouldn't exactly call hate, more like the person just finds Zazu annoying (which I can see, as again, he's comic relief, and some people find comic relief characters annoying). In the end, as has been said, it's all personal preference. I know that can be hard to accept, especially when you don't feel like the other person is being fair, but it is something you have to deal with.
Trust me, I know how it feels. When you're like me and you like a character such as, say, Scar, it's even harder. I often have to deal with seeing people (not as much on this site, but elsewhere) posting blatantly hateful and disturbing comments... people who say they want to stab him, shoot him, torture him, murder him... in some pretty graphic ways. In fact, when I browse for screengrabs or watch clips on Youtube, I almost never read the comments anymore because I just know somebody is going to say something that'll piss me off. Really there's very little you can do in these cases except try to avoid it or, if it comes to a confrontation, try to explain why you like them and ask that the other person respect your opinion (this is assuming they are rational. If not, I just mentally flip them off and continue on my way).
Like why don't you say that to my face, heh? But yes, I know, people bashing your favorite character
really sucks.
... In summation, though, no, I don't think Zazu would deserve that much hate. But, fortunately for you, he seems to be regarded in at least some esteem. Not to mention that most of the people I've seen here at MLK are pretty open and understanding, so luckily we don't have to deal with that as much here, you know?