I'd rather GW focused on providing plastic sets for their infantry choices for the established armies before inventing new stuff. Craftworld Eldar have a massive range of sets which should be available in plastic, like pretty much all the Aspect Warriors (easily six to seven kits), Rangers, the Vyper, the Avatar and Phoenix Lords...

The Dark Eldar could do with (but don't need) plastic Mandrakes, Incubi, Grotesques, pretty much all their special characters, Necron Flayed Ones, Ork Kommandoz, Tankbustas, Warbuggies and Wartraks, etc. Plenty there that already needs work without branching out into new stuff.

Not saying I don't like new stuff, I'd love Exodites, Squats, a bit more added to Harlequins and Genestealer Cults to bump them up to the size of the Adeptus Mechanicus list... but priority should really go to the factions that need it most.