Yes, casters in 3rd Ed and earlier editions do tend to dominate and overshadow non-casting/magic item using classes. I routinely played casters in 3rd edition for that reason. As a limited example of caster versatility: Clerics could cast Divine Power, a simple 4th level spell that essentially turned them into a fighter of the same level, then there was Freedom of Movement, another 4th level spell that made them immune to grapples, and also Death Ward, yet another a 4th level spell that made them immune vs. many undead effects, etc.
I would agree with the earlier comment regarding system mastery in relation to character dominance for 3.5, though mostly in regards to casters. We had a charging frenzied berzerker that could jump 50' and inflict 300 HP damage per round; Deathless Frenzy allowed the character to continue to fight at negative HP for essentially the entire combat (he went down to something like -500 HP and had to have the cleric cast 5 Heals on him).
You can read the character optimization boards in many forums to find people exploiting infinity loops and other rules flaws, even in 4th Ed. Though I must say that while I understand the need some have to make casters "special", in no way do I ever want to see casters be as dominant as they were in some older editions.