Not buyers remorse at all. And how is it a scapegoat? Like I said, Monster Hunter on the WiiU, huge amount of people are playing. The game sold really well too. Also you can't say "if enough people aren't playing your game"... when you don't know if people would buy the game on the WiiU or not even if it had the multiplayer. For all we know, it could have sold really well.
You keep bringing up MH3U, but I have to wonder what you define as a "huge amount of people". MH3U for the Wii U has only sold approximately 400k units worldwide. I would guess that, tops, there are maybe 2000 people online at a time. Where does that estimate come from? See games like the CoD games that sell well over 10 million copies worldwide primarily between two systems. When looking at those, if you've ever played them online and paid attention to the number of people online on a game series built around multiplayer anymore, you'll see that 100,000+ is a huge number of people online. 2000 is just enough use to justify paying server costs. Honestly, most people who will buy a Wii U will buy it for Nintendo first party games. Those games are not games even remotely built around any kind of online functionality. As such, Nintendo consoles draw a crowd that largely couldn't give two shits about online gaming to begin with, thus, small numbers of online players.
You can't blame developers for yanking online multiplayer in games until the Wii U install base increases. Right now, with the number of Wii U's sold compared to potential sales leading to a projected estimate of online play, it would pretty much be a ghost town online, with any profit from the game selling going into feeding server costs. It really just isn't worth it.
Honestly, I'd rather see them yanking a feature that, really, barely anybody would use and just releasing the game anyways versus withholding the game entirely because of the Wii U's tiny online presence.
Once again, the Wii can be blamed for Nintendo's lack of a large, strong console based online community. Nintendo didn't do jack shit with multiplayer on the Wii, and a lot of what they did do, they did poorly. Because of this, anybody who wanted an online experience from their home console picked between the 360 and the PS3. Now the majority of people who play online via home consoles have established some sense of brand loyalty and will go right back to Sony or Microsoft once more next gen rather than stumble into the unknown that is Nintendo's online.