Those were expansions the Dragoons put into gain more firepower so they could go fight the Clans, and have Blackwell prep for Star League and Clan tech production. The Imp isn't too bad since it added in better ranged and close in capability, but the Marauder II is pretty bad. It's the same reason why the Annihilator became closer to its Star League era model, but forgot to put in DHS to add armor, which a defensive mech like the Annihilator needs. I'm not a big fan of the real late Annihilator variants, especially the dual Improved Heavy Gauss, since it has no real back weaponry.
As a side note, I'm working on a homebrew update for the remaining Dark Age intro/secondary and primitive tech units to get some modern upgrades, as some of the Periphery States can't afford to have older assault mechs like the Ymir or the Marauder II-H around given the proliferation of tech across the galaxy. The Devastaor 1-D that the Taurians have is the first one on my list.