I don't know why anyone could/should hate Nintendo. Sure they tend to make family friendly stuff, but their products are of very high quality. Their games are among the most polished on the market.
They do tend to be on the conservative side of things when it comes to franchises, which may annoy some people.
And they've been very slow to jump into online gaming. They do have a lot of catch up to do when it comes to that, but really... Are those reasons enough to actually hate them? Nope.
People will hate on anything irrationally anyway. Be it Sony, Apple, Microsoft, Nintendo, anything... Ask them the reason why, and they'll start grasping at straws and not making much sense.