Yes, you can summon other people and a few NPCs before boss battles, if you've completed certain requirements, but how about optional NPC partners throughout the game? You can level and spec them however you want and they can bring an extra layer of strategy to the game. If the AI doesn't suck and you can order them to be defensive, distract certain enemies, or be heal/magic happy, it can make things more interesting. Plus, we can get way more wacky banter this way.
If someone at FromSoftware gets his/her hands on this, make it happen.