Here are my two cents: Peter and the Lionhead development team have consistently harped upon the concept of "Power" and making the gamer feel as if they are the single most powerful entity on the planet, with the ability to do good or make people cower in fear as they so choose. Focusing on this mindset (and it was previously mentioned by another poster in this thread), it would seem logical that spells included in the game should have an epic feel to them. Now, a fireball may be well and good to some, but it is repeated in practically any game that has spellcasting. If we are truly going to be spellcasting deities, we need something with a bit of kick, something that will make the gamer looking at the screen say "WOW! That spell was amazing!" Personally, after X-years of gaming, a fireball spell will never again make me feel that.
People have suggested earthquakes, tornadoes, meteor showers... this is more along the lines of an epic spellcast. Obviously, low level spellcasters should not have access to these abilities (you may disagree, this is my opinion), but as your gauntlets level up, perhaps their associated abilities should become more epic in scope.
All this having been said, I love the Fable series but would definitely love to see more interactive and more epic magic usage available for this newest version.