For me, the problem with balance is that too much pursuit of it leads to an unbalanced role playing game. A role playing game should, in my opinion, balance the focus on both gamism and simulationism - not focusing not the gamist aspects at the expense of the game's ability to simulate its genre. Gamist structures are there primarily to make the simulation playable, but not necessarily strictly equitable. This is why it's not only common to see wizards and priests with reality warping powers in fantasy games while martial characters lack them, I think it's appropriate. Giving such powers, in considerable numbers without some kind of equipment (which is certainly possible to do), to martial focused characters places the gamism above the simulationism and, I think, throws the balance between the two issues out the window.
For some genres, a more strictly similar result between "magical" and "martial" characters can be appropriate. Take any of your typical superhero RPGs for example. There's no real prejudice between what a swordsman and wizard can achieve in terms of mechanics. But then, that's the superhero genre. It's not really the fantasy genre, though, either with pulp swords and sorcery or with a higher Tolkienesque fantasy or even with D&D-influenced Steven Brustian fantasy.