yes, of course the place holder fillers are great and automatic inclusions. no doubt. it's trying to fit in ones that are not in the pre-existing unit lines that can pose a problem. what techs would unlock them? does this make it uneven between rivals? what do other civs get? should there be a balance? what about stats? is their wiggle room to differentiate? basically, adding ones that aren't already in the unit lines means a wholesale revision, which is not fun unless it is intended to revamp the whole kit and caboodle.