The whole point of having the armor and repair is to make an inefficient static useful. As far as I'm aware, the repair option is just counterplay, which is both intentional and healthy. There is nothing less fun than sitting there while artillery destroys everything you know and love while you can't do anything to stop it.
Specifically, gausse serves as a realistic wall for wolverines, tremors, and firewalkers, all of which desparately need something that they can't just chew through.
The solution is to shoot something else or to kill the workers. Both are very doable.
And might I mention that repairing with ten workers is not "free". Ten convicts is 1400 metal. Gauss is 400 metal. The solars to repair with 50 BP is 1750. If someone invests this much in having one mid-weight static survive artillery, they can bloody well keep it.
I guess I'm open to the notion of adjusting repair costs, but this does not seem like a good reason.