To be fair, that's because the leap from 360 to PS3 to their successors wouldn't be so much of a leap from the 360 [or] PS3 to the Wii U in terms of audience. There's probably going to be more overlap for the first group than the latter (though we'll see how that turns out).
The annoyance and minor frustration is certainly understandable. For most people, that's all it is; they're happy to see another game, but a bit peeved that they might not get to play it. The outrage and seething hatred is from a loud, obnoxious vocal minority.
That's still pretty ridiculous. Pretty much all the reasoning for their complaints is that "Wii U is a kiddy console". If you want Bayonetta 2, you have to buy a Wii U, a new console. Having it release on the PS4/720 would still result in you buying a new console.
The annoyance isn't understandable at all. Everyone complaining needs to think about it like this, the game wouldn't even have come out if it wasn't for Nintendo.