Because effective button pressing is important.
As a shotmage you will require ALOT of hotkeys for spells, we don't do as quick consecutive damage as melees or gunners so you will be firing alot of spells.
What you need to do is go to Options
then Key Configuration
and reconfigure the Short Cut (PC) section and change hotkeys such as F12, F11, F10 to something closer to your WASD buttons, such as R or E. For example I have my "PC 15" and "PC 16" Hotkeys set to R and E instead of - and + so you dont need to reach over that far.
Something else to consider [for anyone reading this far] that's always worked really well for me and anyone else who's made it past the initial adjustment period. For players who don't use wasd to move and are already primarily using the mouse instead, this alternative works even better for mages [or players who have a bunch of toggles they turn on/off regularly] and gives you easy access to up to 32 [that's right, I said 32,] skills simultaneously with the bonus perk of not having to glance at your keyboard to constantly make sure you're hitting the right keys.
Instead of the defaults; in order, your keys are qwer asdf zxcv tgbh [or qwert asdfgh zxcvb if you use something other than the 4x4 layout, but you get the idea]. The advantage to this layout is that you can position your left hand on the "f" key [as though you were about to start typing normally] and can focus more attention on the screen than on watching your keys.
'Course, that's just your 16. If you go into Options, and set your windows from the max down to two, you can set another key [I have a REALLY weird setup, so it's TAB for me; pick what you want] as your skill window toggle. Now that you only have two skill windows, this will effectively let you switch back and forth between the two easily during combat. This works great for enhancer/shot hybrids or enhance/hex hybrids, as you can set your curatives on one tier, and your hex/destro on the second tier, but still have them all a key flick away.
Pros: Great for people who play by memory/touch. Gives you access to more skills. Lets you focus more on the screen/combat than on what you're doing on your keyboard.
Cons: Difficult to adjust to if you're too accustomed to wasd. Since you're relying solely on the mouse to move, sometimes you'll accidentally change monster targets while attempting to move. Not beneficial at all to hunt & peck typists.
Handy Tip: Make H a skill you don't use as often as the others since you do have to stretch a little to reach it.