As with OP, I too would like (at least an option) of disabling that feature. On the worst, it can be downright destructive (has only been the case once or twice with a mate being AFK at base), in the least, just a constant annoyance. I build big and beautiful (as a goal, not nessesarily a result), and constantly having to run out and fix or administer rigeous punishment gets old real quick.

My current build is a bridge spanning a river mouth with the central pontoon being a fort with docks. It's still WIP and assaults have thusfar been mostly irrelevant, but I am keen on getting to the planned village of hovels and small farms on the bank of the river, and that might get.. annoying. And not a chance in hell that gets a moat.