Companions seemed like a good idea, but as enemy-only abilities like fly, nerfing BimbAzzy, and buffing Brint show, they're taking their rpg system seriously, the enounters are balanced around the idea that you're coming with a squad. That's why you either fight hordes or glorified minibosses.
The low level cap was a mix of Savin hating power fantasies, so with Kasyrra being 20 there'd be no way they'd ever let you come that close to her, and them realizing that they're to lazy to come up with X amount of abilities and passives multiplied by 5(6) to pad out those 14 levels. How they plan for you to beat somebody twice your level is beyond me, but we shall see. Most companions having BST than you just adds salt to the wound.