Heh... if I thought stories would work without them I would maybe not use them...
The thing is, actually having a player as a Captain was troublesome in a player dynamic and relation sense. Furthermore, there was the idea that a Captain really should be rather good. I could make everyone else rather good as well, and make it some sort of hyper-elite crew, but then the long-term development is no good.
An NPC Captain solves that problem. But then you have the same problem I have with Kuylen- why doesn't he do all the dangerous work for you? Kuylen is a bad guy so he can always do bad guy stuff and not care for you etc. Dallas is not a bad guy (though some of you may think otherwise, heh...) and he would not leave you in the lurch.
So the accident at the start of the game served a double purpose- to demonstrate Dallas' extreme lack of patience and rather hazardous approach to things... and to make sure he could advise, but not directly aid, you, hence your achievements would be your own.