| Dirty 'n Evil |
Quite frankly, the problem is with your players who want to have thier cake and eat it to. (snip) so the answer is... challenge them to man up and go for it despite surrendering a bit of their thrones.
There's another facet to this problem, perhaps it might shed some light on the issue. I have one player in my group, and he's got a bit of a lean towards the power gamer side. He only plays tank oriented Fighters or Barbarians, or maxed out with every advantage Wizards. Not much variety or difference between his characters... and they always invariably become that main consideration in each and every fight, because he builds them with greater thought towards game mechanics than personality.
This creates situations where the classes with "gimmick" spellcasting always feeling like they're playing second fiddle when he plays one of his tanks... they're not his peer, and feel like their less effective spells don't contribute sufficiently against his Conan-like methods. Contrastingly, when he plays one of his Wizards they're clearly more reliant on the protection on the warrior types to protect his hide, but it always seems like it's always that Wizard's spell that tips the scale of battle - not the action of any other characters.
So, I have players who dislike the variety of the classes with lesser spell casting because they don't want to trade diversity for lessened effect. They see how the game master du jour has two choices... they can make a combat that's challenging towards this one player's characters and almost frustratingly difficult towards everyone elses', or they make it challenging towards the group as a whole and watch this one player's character pick apart the encounter like Wayne Gretzky vs. the NJ Devils of old.
I've tried encouraging this player to try something else... a Rogue, for goodness sakes! But they're not interested. So, I've been thinking of a way to reward the players who do take a more varied path with their characters rather than punish the one player and making him feel picked on. And it seems like spellcasting is a key issue of contention.