Reasons:
Ice and Fire dragons exploitation with the bed.
Some already op pets (such as Tremorsaurus and dragons) became even more op because of this.
Human mobs such as pixies can be treated as a pet despite they clearly arent an animal.

If anyone want to enable the exploit then they can jusf edit the config

Agreed. I had a mod that allowed the player to tame Ocelots again, but the respawn at bed mechanic broke their AI. My Ocelot acted untamed after a respawn.