OK, I see your question now.
I was making the point that, despite what I often see posted here about wizards being better than fighters at everything, they are actually not as good at actually doing damage to opponents. their ability to ablate hit points is far worse than equivalent level fighters.
i.e. fighters are currently better than wizards at a major element of combat.
Thus my point stands - if wizards are less good at finishing a combat with damage, but have more general utility, where is the problem? Presumably in the save-or-end-fight spells (which are a bit of a gamble - and is the issue the presence of the spells or the ease of cranking up save DC? What if save DCs were always 10 + half caster level and saves were always + half defenders level, and classes have one strong save with +2 on top of that - and all ability bonuses were ditched (both on DC and save)? Would a base 55% save against equal level foes be OK? or should it be a better chance of saving? Perhaps DC is just 10+ spell level with no improvements, so 1st level spells are always just DC11 to save?
Is it the plot bypassing spells? What if they were rituals that could be learned by anyone with the appropriate feat (as per 4e)?
Wizard power in combat doesn't come from pure damage spells though - nor does it come from SoDs, to be honest. It comes from battlefield control. You could do direct damage to maybe kill off one enemy, or throw a wall of force between half the enemy and your own team, effectively "killing" far more, or at least ending their threat. Or summoning several monsters to stand between them and you to act as a "living" wall. Or fog spells, or...you get the idea. What wizards do is turn a fight against ten enemies into a fight against one (with nine trapped in various methods of control) and the one left is blinded and bewildered.
...If the wizard is being nice.
If the wizard is not being nice, then it's flying and invisible and then uses a polymorph spell to become a better fighter then the fighter and then a summon spell to summon more fighters and that's the end of the fighter. Or it cranks up the SoD to hilariously high - if not flat out unbeatable - levels and then destroys everything in one hit. Or it never even interact with the bad guys and instead just teleports past everything entirely.
And that's just the wizard. This isn't even touching druids or clerics who took the name "CoDZilla."
See, here's where I think a lot of people get blocked off - combat isn't just about damage. If anything, in 3e and 4e, damage plays a relatively low role in the fight once you get past levels 1-3, unless you can successfully one-shot a baddie. Being able to control the fight is what wins it, and that's what wizards do best - not blasting. Web, not Acid Arrow. Sleet Storm, not Fireball.