^ 100% agreed.
Your equation leaves out when the low DC sorc gets 0 DPS on Evade, Evade, Evade. I saw soooo many evades until i decided to TR and change my DCs. Evade is very common and highly annoying. If you prefer to use only spells with no save then your argument is fine, but there's so many good damage spells that supplement your arsenal, DC are simply too good to ignore.