Basically, an optimized melee can just keep pace numerically with a cleric, druid, or other buffer, and they can't do the other cool stuff. And the ToB classes are actually not all that hot; after more than a few rounds, a fighter or barbie can catch up in damage output. Where fighters excel is in their versaility and their feats, but getting that into play can be a big problem. You can't disarm anybody if you're on the wrong side of a wall of blades.
So in summary, even though the fighter is stereotyped as a "meat shield," a necessary pillar of the party, in actual play, he's kind of a fifth-man class, more like a bard. There are things a fighter can do that virtually no other class can do, but in order to do them, he has to not be blind, paralyzed, held, dead, levitated, behind a wall, grappled by a Huge creature, or weaponless.
So practically speaking, wizard and cleric is a better party than a fighter and any other character. A fighter can be a decent third man, but he's competing with a rogue, bard, or multicassed wizard for that spot. At the fourth and fifth party members, you can talk about a fighter making more of a difference. Don't expect to be the star of the show, though.
Pathfinder goes a long way toward fixing the fighter, by beefing up his abilities, and weakening competitive abilities, like wildshape, animal companions, summon monsters, and so forth.