I'm not really sure... Maybe just to prevent power creep? They didn't want all the best year one armor to be brought up, because then people would keep using the same stuff and not have incentive to work too hard for the new armor... But they kind of failed at that. Other than graviton I don't use a single one of the NEW (not year 2) exotic armors. They just aren't impressive or useful to me. They kind of explained it for weapons. There was only the mida in year one, but year 2 brought 4 exotic scouts, so they chose to leave the mida behind. They brought the red death and Juju up because the only exotic pulse rifle is a reskinned strangers rifle. This entire thing is just a cluster-blam!-.