Here is why I didn't switch to Pathfinder (or 4e)
D&D 3.5 is probably the closest that any mass-produced RPG will get to the game I want.
When our group was playing AD&D 2e back circa 1998 and '99 we had to house rule the heck out of it to make it something we could really get behind. We had house rules regarding multiclassing, dual and multiclassing, racial level limits, raising ability scores as a character levels up, and an elaborate set of proficiencies that granted special abilities in combat or with magic, and we allowed a lot of 1e classes in like Assassins (modified to go up to 20th level) and Barbarians. We even had a homebrew psionicist/fighter hybrid class that was to the psionicist what the ranger was the the druid or the paladin was to the cleric.
When D&D 3e came out, we were very happy to see that the changes to the system largely reflected the direction we wanted D&D to go, just mounted on the more robust d20 system instead of the AD&D mechanics. It was kinda eerie actually we had precursors to fighter and metamagic feats, the psychic warrior, the 3e multiclassing system et.al. If I didn't know it was impossible I'd swear WotC R&D had been looking in on our home games.
So we snapped up D&D 3e with gusto and switched over quickly and pretty much in unison. As we played the heck out of it, there were cracks and flaws in the system that popped up and needed house-rule fixing, but nothing anywhere near as major as there were in 1e or 2e. When 3.5 came out, it fixed some things that needed fixing (front-loaded class features), and some things that didn't need fixing (pokemounts), but it managed to be even better than 3.0
So, my house rule list for 3.5 is pretty short, way shorter than it has been for any prior edition.
4e is a complete other direction for the game, and something totally unlike the game I was playing. For the first time, a D&D edition change was to something that didn't seem like the logical growth of the game, but instead a totally new fantasy RPG with the D&D name bolted on it. 4e was right off the table.
Pathfinder is fine and good, but it was also unnecessary changes. I recognize it as the torch-bearer of the 3.x design lineage, but I've got enough 3.5 books to play for quite literally several lifetimes. Settings, splatbooks, suppliments, miniatures, core books, for campaigns for the rest of my life.
So, I don't see the need to upgrade from 3.5 to any other game for my D&D needs, and I've got enough 3.5 to satisfy me.