[It has more to do with individual responses to illusions; some people don't like their perceptions messed with, understandably.]

Of course, if you like. It doesn't take as much concentration for smaller things but the more encompassing the illusion, the more difficult it is to maintain and do other things. And of course the more energy it consumes. [The one thing Ienzo does miss about Castle Oblivion was that the whole place tended to facilitate illusion magic.]