I agree with Sonia.
Reasons to leave animations out are pretty subjective, too. I would say
leave out animations on all bullet slides unless you have a really crowded
one. In that case, I'd use the animation to help the audience distinguish
one bullet from the next. I'd also use animation if there were something I
really wanted to hit point-by-point. Otherwise, yeah, I'd leave it out.
Another rule of thumb is, if the animation makes you go OMG or laugh or roll
your eyes or say WTF?, then you're better off without the animation. If you
see an animation and think, "What was the point of *that*?" then leave it
out.
If you have something like a line chart showing an upward trend over time,
don't animate it with a wipe from the bottom of the slide. Instead, wipe
from left--in the direction of the growth. Column chart? Don't have the
columns fly in from the left, have them "grow" (wipe or peek in) from the
bottom-up.
Does that help at all?