That's true, but it can still be quite frustrating. I once had a fight between my Cleric and a Wizard/Cleric aiming for Mystic Theurge. You'd think the Cleric would have the upper hand, but my enemy used a Wand of MM and just gunned me down (some caveats apply, but the essence is that even though I only failed one or two Concentration checks, it bought enough rounds that I died from raw MM damage before I could take her out).
Coming back to casting times, I often wondered whether more powerful spells should have times of one or more rounds. To my mind, there's no real way you can rationalist a Fighter capable of hitting people with a big weapon, however good he is, with a Wizard capable of world-shaping magic. The magic should be way more powerful than the sword, but this doesn't lend itself to game balance. Having spells with very powerful effects but which are quite hard to make work could be quite interesting, though in D&D even just a one-round casting time can be significant since you don't even need people to ready actions to interrupt you.
Coming back to casting times, I often wondered whether more powerful spells should have times of one or more rounds. To my mind, there's no real way you can rationalist a Fighter capable of hitting people with a big weapon, however good he is, with a Wizard capable of world-shaping magic. The magic should be way more powerful than the sword, but this doesn't lend itself to game balance. Having spells with very powerful effects but which are quite hard to make work could be quite interesting, though in D&D even just a one-round casting time can be significant since you don't even need people to ready actions to interrupt you.
