This is probably one of the least likely things that would ever be talked about, perhaps even the most non existing thing ever to be talked about. I’m pretty certain that some people on Brave Frontier know that along the lines of the new more powerful and more destructive units that are included in the game, while the old units in the game no longer are considered the best units to get anymore these days for doing the future quests in the game. Not many reasons come to mind other than for filling up the unit guide layout or just to fill up your collection of units. However some people might (or might not really) miss getting those units for the most parts of the game. The only thing I ask is that it becomes possible to acquire those said old units in either the story quest or in vortex quest at a certain percent chance.
Some of you might be telling me “that’s a waist, why would we need those units really if the new ones we’re getting are actually far better than the old ones?”
Short answer is because they were actually the most decent units from back then, but it would be better if they were acquired for free instead of cost you gems to acquire since most likely people would not be waisting their saved gems on old units from the past.