Thing is, would in game objects and characters react to a bumpy surface like that, as they passed over it...that would be impressive, but i can see the physics drain on the CPU would be huge.....
lol, its a graphical improvement, nothing more or less. I can't even think of a game that has perfect interaction between character and the ground, most movement/jumping/crouching in too many games to count looks shoddy, off the top of my head Lotro, you run around but the steps you take don't match up to the ground, theres elements of the same foot sliding in different positions. Thats how most games are, as for benchmarks that are designed to push the limits, well, its never surprising to see the overuse of effects so the benchmarks actually show up differences in performance.
Tesselation killing performance in one benchmark, or even one game, doesn't mean it can't be used in another game for a far lower performance hit. One game could use it, kill performance and it look crap, while another game uses it more, it looks vastly improved on standard methods and it doesn't cost any performance.
Thats why its always hard to gauge how much things help, hinder or simply don't work at all for a while. But as with most games, smarter people, smarter teams with more budget and time, tend to make better engines.
The most interesting thing will be the first game to forsake DX9 completely to build a ground up dx11/dx10.1 game, though thats likely a while off, Shattered Horizons I saw it suggested it would be dx10-11 only, no dx9, but no clue when thats out or have high hopes for Futuremark(if i'm thinking of the right game) making a fantastic game, but it might be a laugh.