From what we've seen, there's only speculation at this point. Unless a data miner found something and has yet to share with the class.
One possibility, which might sound stupid but if you consider other dev fails in the past isn't quite irrational; perhaps the devs don't know how to code other units into the EP system. Meaning, if they did EP again, it would only be for TLJ units. They haven't figured out how to code naval assault units into the EP system.