But whe had all of that allready. And it was removed, because it maked problems.
That the pet is damagable is a pain, because because you dont have the time to give the order to flee and to run in a safe zone yourself. At last, if you dont has the Mode active, that its following you and stand near to you. And even that is messy, when you look at the chocobo, who allways stand in aoe fields.

And than would whe have again, that you summon 1x the pet and dont change it afterwards. The people allways runned only with ifrit, because he was the most usefull of them. And that didnt fullfilled the summoner fantasy.
Or are you meaning, that the carbunkle would by together with the summon skills be used (one problem is, that he is currently useless)?
That could be become to much by itself. With where to place all the Extra buttons, you mentioned (the 2 or 3 skills for each of the primals + Player own skill + Bahamut/bird + seperated skill for carbunkel?
For the moment wouldnt i know, where to place all that skills, to not become confused or, to have them at a nice place.