One might also see destruction of bridges as player created choke holes that encourage the fight / defense. Especially, if they can be rebuilt and provide a fair fight. Besides, if you think destroyable bridges kill game play, then what do you think of dr7?
I think he's deadly.
I also think that even if he initially agrees with you, I can convince him otherwise in less then five minutes.
Here's the MA scenario: Two vehicle bases and two groups of players are on opposite sides of a river with two bridges the only way across.
Group #1 is wishing to continue a tank battle that's been going on for awhile and has asked flying countrymen to refrain from killing the enemy tanks on the other side of the river. Much like asking bomber guys not to kill a CV.
Group 2 is a squad that wants to kill the fight here and force their countrymen as well as Group 1 to move somewhere else. They blow up both bridges and leave, knowing it will be 15 minutes before their v-base will be "threatened" again.
If you're in Group 1, or the countrymen of Group2 in GVs, are you really going to wait 15 minutes to see if the guys in Group 2 blow up the bridges again? Will you wait 5 minutes, or two minutes?
AH is intended to be an action game. If you extend this scenario across an entire terrain, it's clear to me that destructible bridges would not be used as choke point for GV battles but as targets for Jabo sorties instead. You can still "defend" them in GVs or Jabos, but you'll need to blow up the enemy tanks on the path between the two v-bases instead of killing the shacks and leaving.
Scenario #2, the SEA: The Nieman Scenario had destructible bridges that stayed down for the duration of the frame. They were destroyed in the first two or three minutes of each frame stopping all GV advance and killing any chance for serious GV battles.
The Karelia Scenario had a couple of destructible bridges that would stay down for 15 minutes. A swarm of jabo came in and destroyed the bridges. Except for a single squad of GVs, most of the defenders left, afterall, the frame lasts no more then 3 hours. At about 13 minutes, the attackers showed up with an overwhelming combined attack force to kill the remaining defender. The bridges started popping up as the one sided slaughter ended. The defenders were simple kills to be added to the kill point score as the attackers rolled over the nearby GV base.
You can focus on the lesson of timing and defense, but the GV defenders who sat in front of their screens for 15 minutes without action lost all enthusiasm for defending any bridge.
Scenario #3, the AvA: The AvA has several terrains setup specifically for Tank battles. One, avasml, has a town straddling a river with v-bases ~1.5 miles behind the town on each side of the river, and of course three indestructible bridges. The terrain has been used frequently for a popular tank battle setup called Battle of Berlin by Jaeger1 (captain1ma on the bbs). Unless I'm mistaken, Dr7 has participated in several AvA Tank Nights.
btw, none of the bridges available in either the new TE or OE come as singles. They're unusable for river crossing. I wish it weren't so and I requested one but we'll have to wait and see.