We-Ko-Pa has 17 rolley-polley tee complexes. There are flat areas on each of them, but the tees could certainly incorporate rolls.
During research for an article on Robert Hunter, I spoke at some length with Jim Urbina, who noted that Hunter believed teeing grounds and complexes should reflect the natural landscape just as green complexes do. I replied that I agreed and read him my notes from my pre-opening tour of Ballyneal, where I was enamored of the 17th tee.
On a hole where bending the ball could be advantageous, I love the idea of being able to tee the ball a little higher or lower than my feet. Could it be overdone? Of course. But I don't think tees need to be perfectly level than I believe greens or fairways need to be.