As did I. And you forgot something. Whether or not you even let Garrus and/or Wrex join your crew will likely have an effect on the story. Also, can you believe that you can romance Garrus and Tali, along with all the romances with the rest of the crew? There really giving you a lot of choices.
It's funny you say that...I've read the official list from Bioware and that thing about letting who you join wasn't on there.
I actually wonder if you can actually not have them on there. I haven't tried it, but if I recall, the "optional" party members (going by dialogue options) were Liara, Wrex, Tali, and Garrus. That leaves Ashely and Kaidan as the two compulsories, and one of them dies.
Did you ever try not letting anyone on your party VG Man? I just remember that Garrus, Wrex, Liara, and Tali were all Main-quests, and not just optional, I think?
Also, here's the list I've been going off. This is from the Bioware site:
1.) The decision to save either Kaidan or Ashley.
2.) Whether or not the player kills Wrex on Virmire.
3.) Whether or not the player decides to save the Citadel Council at the end of Mass Effect.
4.) The player's choice of love interest.
5.) Whether the player spares or destroys the Rachni Queen at Peak 15.
6.) The player's treatment of Conrad Verner.
7.) Whether or not the player completed the UNC: Asari Diplomacy sidequest.
8.) Whether the player chose to allow the Alliance to conduct experiments on Nirali Bhatia's body.
With reference to no.8, I chose to give the body back to the husband, and stop the alliance tests.