I like the idea. It will allow to have more interesting approaches for pet-based builds.
I am not experienced enough with Grim Dawn (just 600+ hours according to Steam statistics and most of that time was played with new masteries from mods). So I cannot predict how unbalanced some builds can become. Future will show us.
Would binding pet based procs like āarcane bombā to a pet skill cause such a big balancing issue when the proc rate can be adjusted accordingly? I mean look at word of pain in max range with all the DoT ticks on huge enemy packs. Did I oversee something or would pets procing pets would actually be a thing? (Beside maybe engine limitations). Would open up some nice combinations and more build diversity. Especially for more lazy build
The problem with binding pet skills like Arcane Bomb or Elemental Seekers to pets is more mechanical than it being a balancing issue. The game is not designed to work out and handle a pet of a pet of the player.