Hail Friend,
I find the pet-summoning crystals to be of enormous value to my characters. Too many pets become smitten with wandering syndrome, and the summoner quickly returns them to my side. Also, if spawn becomes over crowded around my char and the pet, and we must flee to heal up, the summoner again has many times been a lifesaver to both me and my pet(s).
Lastly & most recently, my Miner learned a very hard lesson. One of those nasty Blackrock Elementals spawned upon my Miner, killed him, then killed my giant beetle, causing its entire cargo (some irreplaceable) to be lost to decay. My Miner(s) now all use the summoners allowing my U-Haul to remain in safety.
Anyway, those are my thots. If you are on Baja, I'll either buy yours or better still, throw them at me...I will catch em and make great use of em (hehe).