I've felt for months that this entire problem could be fixed by adding Stances or Forms to Sage/Sorc. This is utilized in almost every other class to add to the players current spec. Now this is just a rough idea so dont bash me to hard, but.....
DPS Stance - Something like 5-10% damage boost, and maybe 10-15% movement speed.
Healing Stance - 40-50% armor bonus, and something like 5% to Alacrity or something else.