Couple of things.
1. The tops of the walls arnt all perfectly flat, so you cant just keep repositioning yourself on the wall being attacked.
2. The only way to get onto these walls is to fly onto them and you cant fly onto them once WG has started, unless perhaps you just happen to be flying by and decide to drop in via parachute, in which case I would be very surprised If you allways ended up on the right wall.
Essentialy what Im getting from the OP is that they are unhappy that tenacity is now usefull for RANGED players IF the oposing faction is STUPID enough to continously attack them at 1 point in the WG fortress.
Tenacity up till now has allways been a joke because 20 CC > 1 player with 150 k health.