This. Yes, they have better tools/power to do the things they already could... but with all of that comes NEW things they can and eventually MUST do to compete in the AAA arena.
An example.... Real Time Lighting. Yes, it will save a lot of time/power to have those real time lights, but those lighting elements come at a cost of their own. While you save developer time, you're sacrificing power to get it. As a AAA game, it may be worthwhile to actually do FIXED lighting ala last gen, thereby saving processing power that can be applied to more lighting or more particles or more models or a ton of other things.
In that instance, the ability to do it won't speed up the process at all (except maybe for prototyping scene lighting, could still be great for that situation). It would mean more or less the same work PLUS the cost of working on those additional effects.
Even if you do say use the real time lighting and therefore spent less time on that aspect, you still have people who have to work on improved AI routines, or people who have to work on better model collision detecting, or any number of other things.
As a famous person once said, there is no such thing as a free lunch.