Surely it can be modded, but sadly i cant tell why. The modding people will perhaps be able to help.
It was changed, cause i guess in multiplayer it was fairly OP, it gave the VR players basically ability to bring on 2 titans into the battle, what pretty much upgraded Orkulus is.
I still think making the jump engines one of the upgrades would have been better solution. It was worth at least a try, perhaps it would turn to be balanced enough, while staying actual gameplay option. Which i doubt current solution is, aside from single-player, where its ofc less fun to use than before.