Really, apparently you dont played the Bioware and KOTOR games with much attention.

Perhaps the player answers in the dialogues are a bit simple, but the storylines works good the deep reasons what makes characters act. You can understant the reason what makes Siths elect their path, and in many cases is hard to say if these reason are inherently bad or good, and you have the possibility of become neutral or a grey Jedi how was in my case.

Bioware writers cant know or decide what are the players own reasons for elect an answer or another in dialogue trees, they only put the options there, and we how players have the last decision.

Perhaps these dialogues and options need more ambiguitiy or complexity, but in Mass Effect they add a bit of complexity to player relation with other characters, you can be rude with an character or polite with another. I expect in TOR the ME dialogue trees a bit more evolved. For me how will be the system is pretty clear.