Icons bring an aesthetic touch. I know in KOTC I identified spells by their icons, particularly those on the frequent list. In large battles in particular, the ability to quickly identify and select a spell at a glance saves time and actually adds pleasing ritual to the game. Reading a menu is reading a menu and there is nothing endearing about it.
I'm sure there are artists among those waiting for KOTC2 that would contribute icons if the engine supports it!