I think this is to be expected.
While 4k or even 1440p don't become mainstream we won't see MASSIVE performance jumps from gen to gen.
1080p performance is pretty much as good as it gets seeing from the point of view of either AMD/nVidia.
Even the slightest bump in performance come at a massive price increase(7990, Titan) and knowing the market they get away with it because people will buy it.
Maybe it wasn't the right time for a next gen of gpus and they just were pressured to do it because of the new consoles launch.
As a much of an enthusiast I am I seriously hope they take their time to release another gen of gpus and actually bring something new to table. (Like Mantle, that was pretty nice but it's just one of those things we will have to wait and see).