Caitian and Edoans would have been great and they would have had the ability now to show them live action.
We saw two believable Caitians in ST IV, and the triple-breasted cat lady in ST V.
CGI animating an Edoan would have been similar to doing VOY's Species 8472, but it's a lot of creative energy and $$$$$$ unless the script really needs a three-armed, three-legged Starfleet alien.