I do not agree with the companion being used as a character slot. Unless the player is allowed full control over the companion as if it was a controllable character. For example a mode like Rest mode for companion manual controlling would prove effective.
Also, it is frustrating how lack luster the A.I. is for companions. There is no aggressive attack setting for companions only a passive attack mode. If the player attacks or gets attacked the companion attacks.
Some solutions I would be grateful to witness are an upgraded A.I. for companions and / or Manual Mode Control for companions so that a character can regenerate sp / hp and still control a companion.
The ability to enable a player to instruct a companion pet to auto attack a specific target is valuable even if the A.I. sucks. Still the A.I. is the better fix, yet a manual control mode would be useful.