Wintergrasp has the sin of being counter intuitive. I maintain that Ashran is worse simply because it’s boring.
Honestly I think the solution for WG is something as simple as giving the attackers incentive to destroy those towers- something like a stacking buff that gives vehicles 5% more HP and deal 5% more damage.
But you are right about the tendency for games to snowball- you usually know exactly who’s going to win with about 5 or 10 minutes on the clock.