You have no stats on this, and that's hardly a majority. The internet comment sections aren't a representative sample of the total audience.
Well, pretty much every casual fan I know in real life thinks the same. Yeah, I don't have stats on this. I can't. But that very much seems like a general consensus based on what the direction of the Buu saga was. Likewise, Mad Max was praised as one of the best movies of the year, but there are many people out there, like yourself, who didn't like it. It's impossible to get a true general consensus of the worldwide audience. I'm just going by a common complaint I've seen in various communities, over and over, for 10+ years.
Because Vegeta wanted Earthlings to pull their weight.
And this was pulled out of his ass. He certainly wasn't thinking about it when he played rock-paper-scissors with Goku to fight Kid Buu. It was a bad decision, and just bad writing. The execution, however, was great.
It's not clear how strong he is. It's very vague. Is he stronger than the Super Buu that Gohan initially fought? There's no clear answer.
Goku states he is no match for Super Buu, but clearly stands a chance against Kid Buu. He also implies Gotenks is stronger than himself, who in turn is much weaker than Gohan. Goku is also confident Gohan could take down Buucolo, who should logically be much stronger than Kid Buu, given that he has three people absorbed.
That is Cell being cunning, but it's also Vegeta being stupid. It's within character, but it's well within character for Goku and Vegeta to want to do something on their own, which is ultimately why Goku asks Enma-Daio to resurrect Buu. He wants to get better to defeat him on his own. Let's also not forget that there were numerous ways in which the cyborgs didn't need to be a threat to begin with. Goku and his friends had warning, but instead of looking for Dr. Gero, they trained and put the world in jeopardy in order to fight strong enemies. It's really not much different than the Kid Buu fight.
The Gero thing I agree was as stupid as the Kid Buu thing. That entire saga could have been prevented if they just stopped him sooner. Likewise, so could the Buu saga if Vegeta didn't allow himself to be possessed, Vegeta didn't knock Goku out cold, Goku beat Fat Buu as a SSJ3, Gotenks didn't mess around, and Vegito didn't mess around. The Kid Buu arc bothers me the most though because everything was laid out for them to win. The whole arc just tried to pad the situation in an effort to give Goku the spotlight and make it seem like there was actual danger, which just makes me roll my eyes. That said, it was also exciting and had a much better tone than the rest of the saga, which is why it's my favorite. Go figure.
That's not buildup, that's continually giving a character power ups to maintain relevancy, the bad idea was to force the less compelling character into the main role.
He was only less compelling because the writing made him so in the saga. As it stood, he was the main hero for the majority of the saga. If he was developed better, this wouldn't be a problem, and I wouldn't miss Goku in the lead as long as he's still a major character (which he was in the Buu saga).