3e magic is highly reliable relative to 1e/2e, because "DCs" were very flat across levels. At the levels you had access to very powerful magic everyone can make their save 75+% of the time. We laugh at 3e transmuters who try to polymorph fire giants, but life was usually like that back in the day if you liked interest spells.
As I see it, it was a design decision that every PC's "big guns" should be more likely than not to be effective. Wizards/Clerics got more reliable spells (or rather, everyone got worse saves). Melee characters got criticals, iterative attacks, and tactically interesting feats to compensate.
I would say that Skill-like spells and Mobility spells should all be boosted in level. The spellcasters can stay potent in blasting, area control, mind-bending, and illusions. Nothing wrong with relying on the athletic classes for getting up that wall and into the castle to rescue the princess.