1.) Ninja does more damage than they should, cause the effect of Trick Attack is so big that you have to balance it out by having slightly lower DPS yourself. It has nothing to do with difficulty of the jobs when they balance DPS, cause players with the same skill-level will get better overall results with Ninja.

2.) Ninja has the lowest TP costs of them all, your TP regen theory doesn't change the fact that they have less problems with TP. Why wouldn't they change this?

All I see is excuses from people everywhere... It's not like they are making NIN useless, just in line with the others.

I bet it's just a tiny nerf, and DRG on the other hand, should get a really big Buff, cause with the least amount of utility in the game, they should be up there within reach of Nin and Mnk if it's to make sense...