Yeah, mice have an advantage even over thumbsticks for fast and accurate aiming. Theoretically using the touchscreen could be even better; I recall playing a port of Missile Command on my Psion 5 which used the touchscreen, which made the game slightly too easy, and I've played lemmings on my DS, but those were basically 2d games. Mice also let you wheel round and aim at things that aren't in your current frame of view. Maybe combining a thumbstick and a touchscreen could be also as good, but a touchscreen on a big monitor is quite tiring to use as well, which is a strike against that plan.
