The problem with your argument that you've been laying out for the past few posts, is that half of it is based on your assumption that it would be executed horribly. Maybe it would've, maybe it wouldn't. But I'm not here to talk about that. I'm here to talk about whether or not keeping the trial in ME3 as a way to give flavor and variation to the first mission, and to recap certain events the previous two games was a good concept in general. I say it is, and I say what we actually got in it's place was poorly written uninspired dreck.
Based on prior experience with politics in the MEU, it would've also been uninspired dreck. Especially had Drew Karpyshyn stuck around. I can only imagine a trial in the vein of the council conversations in the previous two games. Remember?

Yeah, no thanks. I'll take the railroading we got, which involves much more palatable stumbles.
Yes because Shepard has always been the one to immediately take action against the Reaper threat, has the most experience against it, and Anderson and Hackett have always believed him.
So ... what's the point? That's actually the argument, along with the issues involved with why, exactly, Shepard was going to be brought to trial.
It's a thorough mess of an idea just for "flavor", a waste of resources towards something that would also earn complaints about choices ultimately not mattering, let alone how this trial would reach "guilty" and "not guilty" verdicts.