Some people dislike their games. Other their philosophy. Others, their fanboys. Especially the last one.
Also, I think few hate Nintendo or Wii U, is just that they don't like their products. Nothing wrong with that.
The fanboy point is a good one.
I owned an NES, the first console I bought with my own money, saved up from christmas and birthday funds, and a SNES. After the PS2 Era, though, I pretty much switched to PC gaming, so I ignored the start of this generation. When I decided to buy a console, I remember coming online to look into the strengths and weaknesses of each. Subsequently, I will never forget making the mistake of saying "well, the Wii doesn't seem to have as many games that interest me." BIG MISTAKE. It was like I simultaniously insulted the mothers of many, many people. Charts were posted left and right, along with a slew of insults and generalizations. When I explained that I didn't care much for Mario games it got even worse.
That experience definitely left me with a bit of anti-Nintendo sentiment when I had none to begin with.
The thing is, I played so many platformers as a kid that they hold little interest for me now. I don't care WHO makes them. However, some people, more than any other genre, believe that you're not allowed to dislike platforming games. It's annoying.
So, yeah, I think the self-righteous attutude of some Nintendo fanboys really hurts the brand, because I have nothing at all against the company itself. I criticism them on occasion, sure, but I have no problem doing that with any corporation.
As far as the Wii U goes, I'm going to keep an open mind, though I don't think it will bring enough value to ME PERSONALLY to be worth getting another console. I have more than enough to play as it is and money is tight. However, I do want it to succeed, and I hope those who love the Nintendo franchises are very happy with it.