>>12528020First of all, I don't think expressing hatred toward Hoenn can be construed as a rebellious act, when you yourself admit it's pretty prevalent ("massive").
I believe the reason why boils down to shock. In RS, players who loved the first two generations found themselves in very unfamiliar territory: they were in a whole new landscape with no familiar landmarks or recurring characters. On top of that, the Pokemon were almost entirely new--only a handful of previous generation Pokemon were part of the Hoenn dex. Compare that to a very nice blend of Gens 1 and 2 in the last generation.
On top of that, the new Pokemon were--and I'm not going to quibble about taste, "overdesigned," etc--different than those that preceded them. I'm not saying they didn't look like Pokemon, but they were distinct from the first 251; there was a stylistic evolution. I think the foreignness of everything amplified how different these Pokemon seemed.
Altogether, these elements created a game with a Pokemon name, and all the right mechanics--but the feeling was unfamiliar, different. Worse, there was no way for players to reconnect to what was previously established--until FRLG (and yes, the GameCube games). Many of your firmly-established favorite Pokemon simply were not available, at all. That may have felt like playing a Mario game without mushroom power-ups... or hell, without Mario.
I realize that Gen V did the same thing. to an even greater degree even, but there were two important differences: one is that you could almost immediately connect to previous generations/Pokemon through a variety of means. The other is that we've experienced, and gotten over, this phenomenon before.