I agree entirely but most of the species you listed have big wild populations and don't need to be saved. Keeping them is more for our pleasure than saving them (I have no problems with that but people are being mislead if they think a breeding program would make any difference for the wild population).
Yes of coarse, but since it doesn't seem enough zoos are only exhibiting animals for conservation purpose and having them for breeding programs, why not add new not so threatened species to a zoo and take away the more common ones. If they have no planes to switch there Greater Flamingoes with an endangered Andean Flamingo why just leave the Greater Flamingoes and not switch them with something that isn't as common?
For instance: The millions of Meerkats. If zoos aren't going to get Indian Brown Mongoose (VU) for a breeding program, why not switch them with Banded or Dwarf.