Vengeance is not a crit heavy spec, therefore you gain so much more if you lay off of surge and crit and pump in more power. Crit increases the chance that your attacks hit for maximum dmg and apply the crit dmg bonus you get from adding in surge. Power on the other hand gives you an instant dmg boost to every attack. You spend alot of points on crit and surge, and only get to use them when your abilities crit. The Veng tree has one skill Savagry that increases the crit chance of Force Scream and Vicious Throw by 60% if you invest in to that. Are those two abilities and a few more crits on your bleeds worth the loss of overall dmg output that stacking power will give you? It is not.
RAGE spec you need the surge due to Dark Resonance giving you 30% increase in critical strike dmg for the instant crit smash ability. RAGE used to need to reach the crit soft cap, but with the change ups made in the last patch i doubt that is the case anymore.
As PVE your time on target is going to be alot, and the more dmg you can get out consistently will matter more than the off chance that your ability will crit and do alot of extra dmg. If you are at 35% crit chance and drop to 30% that is roughly 135 crit, which is about 31dmg that gets added to your characters overall melee dmg and force dmg. If you have a crap ton of accuracy that is over 100% swap that out with some extra power, im sure you will see a difference. When you up your melee dmg and force dmg you also up the dmg you get when you do crit. Going from 3.5/10 to 3/10 chance to crit isnt that monumental and the extra dmg you will gain will be very beneficial.
Just my 2 cents from playing both Veng and RAGE specs.