The thing is that the glamour system will be a thing.
SE is just being logical, they know that players will use 1 or 2 pets. Why would they bother doing 6 or more pets.
Giving a glamour system to players is the best way to make them happy while not doing work for nothing.
If you are bored of your Ifrit or Garuda, just glamour it to Shiva or Ramuh and so on.

That's the best, most logical and less time wasting option.