I agree with everything you said. More squad interaction is needed. But the problem is ME3 is the end of the trilogy and thus the end of Shepard's story. We wont see Jacob's longing looks at Miranda, or a crestfallen Tali crying in the corner (similar to Inara after Mal has sex with Nandi.) after Shepard chooses he wants to be with Liara or Ashley.
If meaningful after mission squad interaction was to happen,it would have to be introduced during Mass Effect, or at the start of 2 at the very latest.
Bringing it in now, would just not fit. Mass Effect 3 is the end of the world. Garrus and his anger over his mothers death is something that would bring out a "suck it up and deal with it" reaction from most gamers,myself included. I DONT WANT to do loyalty missions again in ME3. This is the end of the line, I have gained the loyalty of all my crew, I should not have to regain it especially when, literally the galaxy is at stake.
In a similar way, the Simon-Kaylee romance was rushed. Really introducing it, they started too late. I feel awful about it too, I loved Firefly and Serenity. For Simon-Kaylee to feel realistic, it has to start at episode 4, and by then the crew is still suspicious of the newcomers (and rightfully so.) The show was canceled way too early.
What im trying to say is, I really agree with you. I wish that the Jacob likes Miranda subplot could have come up. I really wish the Garrus-Wrex disagreement subplot would have made something of a difference in ME1.
What I want, in the worst way is for the squad to share a meal every 2-4 missions to discuss developments in the story. (Ie the Reapers just hit the Alpha Relay and the Earth fleets are cut off from the rest of the galaxy. Id like it if the human squad members were really angry and urged me to launch a suicidal attack at them and try to retake the Relay.)
The other problem with what youre saying? The difference between TV and video games is that, especially with Mass Effect, the story is centered on Shepard. The story cant be centered on Shepard for 2 missions and then pan to a cutscene showing Jacob trying to get back with Miranda,unlike how Firefly can show Mal and Inara, but then pan out to a scene of the Serenity. Firefly is not Mal centered, or Jayne centered, or Inara centered. Firefly is about the interactions between the crew members aboard the Serenity and how that fits in with the grand theme.
Mass Effect is about, merely the grand theme of destroying the Reapers, saving the galaxy. During the Firefly series, there is no grand theme to focus on.
I hope my post makes sense. Thanks for reading.