IRC when it first came out it was free and stopped all resource income for as long as it was alive
Now it has a front loaded MP only cost, and reduces income afterwards
Don't forget about the 50% receive damage modifier which made it have double HP.
I'm interested why they never work with this concept with all the heavies in order to "balance" them in comparison to mediums. Give them more HP but increase the damage modifiers so you take longer to repair them.