Awesome - thanks!
Back to the original post - I think the link Rogue provided does shed some light on the companion characters providing tanking/healing abilities where your character lacks. From Jake Neri, and some DH insight:
We have to make sure companions work and we have to make sure people that don't want to have companions have a fun experience. What we have to do is provide options for you as a player to make sure you can customize your play style the way you want. It is really simple. We talked about it a lot today, but we feel each one of these classes has things they are inherently strong at and the companion should provide a different variation on that game play style
During the interview we realized that BioWare plans on using companion characters to solve the looking for tank/healer problem seen in other MMOs. This should come as good news to anyone who has had a gaming night ruined because of a missing class. This will also allow soloers and small teams to retain a level of autonomy if they wish to play by themselves.
I guess my question would then be if we have the option to take control of the companion and let the main character use AI. For example, if you wanted to tank with your companion and let your main character run around behind and attack from range, would you be able to? I think the answer is yes - we saw that type of style in K1 and K2 - so it seems a natural step to allow it here as well.