I do not like vanity pets... or any pet that can't be affected by the environment. So I am not a fan of the current RNGR mechanic that magically/instantly/temporarily summons pets as attacks. To me that is solely cosmetic (i.e. vanity). Unless it is explained as some kind of arcane summoning and the animals aren't actually real, but then that doesn't fit the typical "Ranger" archtype. I find it unappealing to have bears and panthers jumping out of the RNGR's pocket for a split second and then vanish.
I do however love actual pet classes. If the summoner had a mechanic where arcamentals were summoned for a singular attack (similar to the PRotF or the EQ Mage) that would be baller IMO. Giant elemental fists from the ground to crush or grasp an enemy, or a wind saber from thin air to slash the target. I can appreciate the DRU, SHM and SMNR pets. I'm assuming the NEC will have some undead pet, and of course charm is always nice. Their pets can be affected by the environment and stick around for longer than a split second.
I love class pets. One of the best visual examples of power gain is the size of the EQ pets from your tiny newbie pet to massive pets that just keep getting bigger year after year. My hat goes off to whomever though of that effect.
Vanity pets on the other hand can go right into the waste bin as far as I care. I put them right around my lack of love for cosmetic stars or hearts floating around your character that serve no purpose.
If it makes sense for a class to have a pet for utility in some fashion, then yes.
I'm inclined to agree with Vandraad, if you want to have a pet, play a pet class otherwise accept that there are none.
In the case the game decides to implement pets, I would be ok with the following;
Any other pets bought or earned would only reside within the perimeter of that character's home/house and would not venture away from that spot.
Since they do not facilitate the character in any real way, there is no need to have them running about throughout the world.