How do you treat anachronisms like Futuristic Wizards

Futuristic Wizards are entirely OK if the genre accepts them (e.g. ShadowRun). Things like the Arduin Techno class are, as written, much more of a problem as their tricks would really need a large technological and industrial base to support, and thus don't ring so true. Like the old “mages can't use swords” argument, it's best if the players just take any limits as one of the canons of the game, and the worst is to respond to provocation with a tantrum — “I'll ban it forever!”