That could be interesting to try, but I certainly don't mind the uncertainty of winning before turn 10. Variety is the spice of life: the last two games I have played ended on turns 10 and 5 respectively. The former was a 3 way SBG tie on castles, then a 2 way BG tie for barrels, and my Stags scraped by with one more power than the Squids for the win. Exciting stuff.
I agree. Why not up the number of castles needed for an insta-win and hand out points to award the winner if it goes 10 rounds?