Ya, so? Sure, if the wizard is facing them toe to toe or expects it. But if they get the surprise round, *BAM*. If they have friends, while that wizard is casting A hold spell, the others are ontop of him.
Have we forgotten about Silence spells? Grappling? Disrupting his casting? Thunderstones? Tanglefoot bags? Heck, a member of your party could Counterspell his hold. That's an action people rarely take, but if you're really afraid of a hold, then ask your buddies for some help?
It Is a game of paper, rock, scissors, *IF* you fully ignore your weaknesses and focus Everything into your benefits. Who is the smatter, a Troll with a Belt of Giant's Strenght, ring of Magic Fang +3, and Boots of Speed, Or a troll with Ring of Elementa Resistance (Fire) or Armor of Fire Resistance?
As pointed before, your role as a fighter is to Fight. But you're not effectively doing that job if you're A) Helpess, or B) Dead. Your fighter wears armor so he won't get hit in melee. How's that deferent from taking feats/magical items/spells from allies to protect his mind? Even devoting some of your cash load to protections or feats Does Not Take Away your ability to utterly anihilate anything on the field within reach of your weapon. If you can keep fighting, are better resistant to a spellcaster's wiles, then your job as being able to fight more effectively is accomplished.
It is better to survive, and take longer, then to hit hard once or not at all, and die. You wish to be wasp, not a bee.
And, taking the Mind modifer away from a spellcaster to allow a DC is like taking the extra Str damage away from the fighter. Mages live because of their high DCs. If everyone keeps making the saves vs. a 10th level wizard's fireballs, then really, he's just rolling 5d6 damage. And, even at Max, 30 points of damage to something at 10th level is Not something to make a carreer on. An 11th level mage's Disintegrate is a DC 16. Even a wizard with a 10 con at level 10 needs to roll just a 13 to make that.
If their mental stat DC upping goes, then all that does is give them more spells, that will do minimum effects. What other purpose is there for your mage? To beef up the fighter, so he can shine all the time? Ooh, boy. Roll me a character sheet Right Now!
