I have to say, I agree with the OP about the part where Ashara is the weak link of the SI's story. I would have had no qualms shooting her out the nearest airlock or cutting her to ribbons while she slept. Utterly useless, utterly annoying. That said, I really don't feel the need for that Benikos woman either. I have no interest in her character either. This is just my opinion of course, and I know others love those characters.
Is companion character potential wasted in swtor? Yes. Absolutely. There are characters all over the place I'd love to adopt as companions. Captain Beron...Lieutenant Rutau are a couple off the top of my head. There are many others. The biggest waste of all however, is the companions we're already given. There is so much we could do with them. The stories and adventures we could have. The battles, the scraps...leaving, coming back after reconsideration. The possibilities are endless.
Sadly it all depends on one thing: Bioware's inability or refusal to produce these stories for us. I can't hammer away enough at how important having individual class and companion stories extensions is. What bugs me the most is that they've even stopped giving us new dailies, now it's just fps and ops only, and solo players have nothing new. And I really don't care to get into a big debate, about how I should buck up and fp and ops with people. I won't. Nor will I play 'solo' games on my pc, xbox, or playstation. I like being alone in a world populated with other people, with only a very select few to interact with, kinda like real life.
So yeah, yadda yadda yadda, more class and companion story extentions and evolutions.
The Story Lady.