Pets and combat mode
It’s there to disallow you using disposable pets to wear someone down while you stay out of their range.
Pretty easy just to hit the return key(assuming you rebound them, don’t know why memo devs love function keys) and the attack whenever you want run or fight.
I hate the in-combat slowdown, too, but if your pet is in combat, it’s reasonable that you are also. One of the cool things about pets is that they can work for you at a great distance, around corners, etc., when you are just standing there doing next to nothing. I’ve gotten kills in sPvP when someone I’m fighting flees a point and I stay to cap but my pet chases and downs them. Then there’s the uses for Guard in WvW. The ranger mostly just watches as the pet destroys siege and players on top of a wall.
If I’m fleeing, and the pet is dragging behind, in combat, at lot of times a pet swap will do the trick to get you out of combat.
All that being said, the calls for the ability to perma-stow or put the pet in heel such that it won’t aggro are totally valid.