My opinion on this is less of a yes/no to it, but the line of development where i think its worth bothering with.

My main issues with past iterations of "vanity pets" are mostly.

-They all are cut/tiny. I wouldn't mind having a Vanity pet Dog. But they are always purse puppy side. Even if it can't attack etc could you atleast give me a German shepard type vanity pet? to scale? Maybe my dog is a coward, maybe he just growls and barks when i'm in combat. But atleast its not a mini poodle.

- Lack of an emotes involving Vanity pets. This one is usually a pity because it leaves the vanity pet as a small shadow that may randomly bark or animiate but your unable to do anything with except summon/desummon. If they make a vanity pet dog. Let me pet it, throw a ball for it give it a snack whatever. But if all they do is exsist and bark here and there its very blah.

- Realistic isn't quite the word to use, but i prefer Vanity pets to be somewhat withing the realm of game lore as much as possible. I personally don't want to see a baby Ifrit or Ifrit jr Vanity pet. Or the baby version of the biggest baddest dragon out there etc. Marmots, dodos, Dogs, Cats, Bombs, Leaftraps etc sound good enough to me. If their pets i prefer them to resemble pet type things. Leave the exotic stuff to a pet class/job.

Those are my thoughts and opinions, hope you found them constructive.