dx 10 was a pathetic flop compared to what dx11 is. dx11 is the end of the llod model, dx11 has variable llods which scale by distance, so there will be no more seeing the detail model switch back and forth as you take a step forward and backwards at distance x from object y. that alone made my jaw drop when i heard that 2 years ago ( and that it was going to be in dx11).
On the graphical side of a game, because you cannot deny it graphics do sell, having a game that is dx11, or uses some dx11 features would be very handy. hell even if it really dosent even properly use dx11, the ability to say that it uses dx11 will attract more customers ( even if they wont stick around for the long run, they pay dont they?). then over time the game could be patched to use more dx11 features, lets not forget twi's habbit of supporting a game for ~1 year after its release...
(unless of course ut3 cannot utilize dx11...)