The entire loot table needs to be adjusted for Peerless bosses. 99% of what drops on their corpses is unusable. Even some of the regs (i.e. BLIGHT), are just not worth even picking up. I'm not saying they need to make the loot the equivalent to what you get on Exodus or Scalis, but atleast throw us a bone.
Peerless artifact drop rate appears to have gone down since ToL released... however... the other side of the coin is how many Crimmys (and other Peerless arties), do we really need floating around in game? I think that Lady M and Medusa in particular are way over run by most PVM guilds (mine included). The Medusa drops (aside from Slither ofcourse), are only good for Clean-Up points and drop too often. Even the Fey Slayer bow is no longer useful now that the Fey Slayer property can be imbued. While I agree that there needs to be some better balance... I'm not sure increasing drops on Lady Mel/Medusa/Dreadhorn makes sense. Maybe some of the lesser run Peerless bosses (Chief Paraxymous, Grizzle), could use an increased drop rate, but not the ones where you can do 9-10 runs in an hour and a half.
The other idea is to take a page from what they are currently doing with some of the Doom artifacts that are now to be used on Kotl City event recipes... make the lesser used Peerless drops into ingredients for something new in the future.