I only laugh at anyone who bought one thinking that they'd be able to show off in Dalaran for a little while, only to find that there were already 15 people standing in front of the bank on their own store-bought mount. Other than that, I honestly don't care one way or another. I won't get one because I don't think that it's worth it, but if they'd made it a flying raptor I'd have plunked down $25 in a heartbeat...

As for selling gear, the problem with that isn't that people would quit in indignation. I think that a relative few people are even aware of what goes on via the website and forums and blogs and websites. And I also am pretty sure that most people who talk about quitting never do so, or return before their subscription time even expires. I think the problem is that you're helping players skip the content, and moving them through the game more quickly without any effort. Which means that they could actually get bored and quit because of that. Not because they were pissed about anything, but simply out of boredom.

Selling a see-through horse for $25 is just a way to make money. Selling a "Finish WOW with one click" button could actually hurt them in a pretty short time span.