By no means am I the most pessimistic person in the world, but it stands to be said that for every person who can be an animator, writer, and voice actor at the same time, there are hundreds, if not thousands more that can only be one. At most, the majority of people can only do two of the three, and the sheer number of people who use voice altering, or voice manufacturing, programs seems to hint that there can only be one of any type of artistic talent in most people.
That being said, it's also much easier to be a good writer and voice actor than it is to be a good animator. Animation takes years upon years of practice to become good at (depending upon the type of animation). While I may be a fair (but interesting, I've heard) writer, and a slightly sub-standard (I'm working on it) voice actor, animation does not come to me, despite hours upon hours of attempts.
On a more personal note: for those who point to my zero flash animations and say I have no right to critique theirs poorly, foo on you! If a movie is lacking in any of the "Essential Three" (animation, sound, and story), then it is lacking in all. Animation, while still incredibly important, it the least of the essentials. Some bad animation is acceptable if an animation is exceedingly well written and the audio is good on the ears.
In other words: making an animation is not neccessarily a prerequisite for critiquing and animation. All it takes to critique is a discerning eye, a logical mind, an ability to reason, and an open mind. If you have those, you can be a good critic. If you don't, then you can still critique an animation, but you're less likely to be taken seriously. Ah, and you can't forget: good grammar!
Lord! Too many people forget grammar! It's hard to take someone seriously when they consistently say things like "I lold" and "y iz ths so gay".
And if someone wishes to debate the issue with me, PM me and I'll get you my gotmail account if you seem like someone who'd be a good critic. After all, similarly wired minds tend to get along either splendedly or not at all.