Honestly, would you want new companions so easily thrown about? People already complain about ability bloat (which I agree with to some degree) so why would you want to so easily add a new companion and then six months down the road ask for another? Unless, of course, you expect this game to be short lived and not reach the point where companions are a dime a dozen.
I personally would have preferred one (or even two!) less companion, then the HK companion, then possibly a new companion with the release of makeb. I don't want my side-kicks to be rushed. I want them to each hold sentimental value.
I also don't include your ship droid as a main companion.