It isn't really shocking, the environement detail was also FC2's selling point. The fire/Details in FC2 were fun for a few hours but after some time it became boring.
They showed it at E3 back then https://www.youtube.com/watch?v=cfSBHJRU9_Q basically to show of what the engine can do but people seem to not care about it while playing the game.
i agree all that interactivity will be fun for few hours, but imo FC2 story was no funny to play.. and i assume it was the first game on duniya engine.. so with a better story and more refined AI behaviors helps elevates the experience even higher. Its just a shame duniya engine had so much potential but ubisoft wanted multiple trimmed down engines.