It's funny.
When Oblivion was still not announced I would hang out at the TES boards. My god, Morrowind was a fucking piece of shit according to the vocal minority there. Think NMA quality piece of shit. "Whenever they announce Oblivion, I can only hope it matches the glory that was Daggerfall".
Long lists of boycotting Oblivion before anyone knew the game even existed or was called Oblivion (it was assumed so since Beth was on record saying they were going to call TES3 "Oblivion" and IV and "ivion", yeah.).
After Oblivion was announced it became even more vocal. It seemed like everyone wanted Daggerfall back.
Then close to the launch of Oblivion, maybe when everyone was doing a Morrowind playthrough in advance, people warmed a bit on Morrowind. A few months after it was released, around the time I stopped visiting the forums, Morrowind was suddenly not only "underrated" but the crown jewel of the TES line. A thought that's only increased until now most people realize how great Morrowind was.
Of course, with Skyrim coming, a pattern didn't start as people are still saying Morrowind was the great game and they hope Skyrim is the next Morrowind, but I was just remembering the flip flop of pre-2005. ha