Indigo Winged Parrot is another...
I wouldn't necessarily care about rare species being so common that they are available in captivity so much as that they are well enough established in the wild that human intervention is not required to protect the species.
Not all species of parrots do well in captivity... especially when it comes to dietary needs, space or simply because of the parrots natural ability to destroy things and dismantle them. Imagine how difficult it would be to keep a bird preoccupied enough not to dismantle it's own cage. Well, some macaws and cockatoos already do that! Imagine if that was a natural thing for the majority of the birds in that species to do? (The kea parrot... known to dismantle/destroy automobiles - in captivity in a few select areas) Or imagine having a parrot who's natural diet is fungus, moss and lichen.
What I'd like to see happen is for people to stop hybridizing species and subspecies of birds... and for it to be animal cruelty to keep birds in such small confined cages, or keep birds as single pets. If they aren't a member of the family (as a single pet), they should have a companion.
I'd also like to see different hand raising techniques to produce better, more well rounded pets than those who are going to have behavioral issues because they don't know how to be a bird.
One of the main reasons why there aren't more species of parrots being bred in captivity is because no breeder wants to breed a parrot that may appear dull and drab and may have no "worth" to the general public looking for pets, even if the goal of this breeding is to increase the numbers of the species.