I agree that there should be more direct story consequences to the gameplay. After all, it's the epic story/gameplay integration that makes the Mass Effect games so damn enticing to me in the first place. I'd love it if there were actual missions and story elements which were totally different, or available/unavailable in ME3 based on choices made as far back as ME1. For example, a showdown/mission which is riggered if you romanced a certain character or 2, but won't trigger otherwise, or a mission for Garrus which will only trigger if he's been a squadmate for your Shep since ME1. Or maybe missions which van only be triggered if you have lost a teammate. Make it impossible to get all the content in a single trilogy playthrough. Make certain endings only available based on squad wins and losses/ choices made in all three games. Hell, make the 'best' endings only available if you did kill Wrex on Virmire - mix it up, bring it on! Make our choices matter in ways we never expected them to.
I don't think by offering different missions available only to people who took certain paths is a bad thing, or a disservice to anyone who is playing the game. I know very few Mass Effect fans who have left either game at a single playthorugh as it is, so to give me better story/gameplay reasons for my replays would just make me ecstatic. (not that I don't have reason enough alread).
I don't think anyone is saying that if you lost a squadmate you played it 'wrong'. Some of us lost squadmates because we made choices true to our Shep's perosnality. Other people seem to have lost people they did not expect to lose, but that is the beauty of the suicide mission: it could potentially lose you anyone. If come Mass Effect 3 it doesn't affect my party choices, or effect elements of the story in some way, I'm going to feel cheated. It's going to matter less, and I probably won't care as much as I did during this one. My heart was in my chest for a lot of it because this stuff mattered, dammit! If by the beginning of ME3 those 'consequences' come down to a 2 line conversation I can see on youtube, it won't anymore.
I know, I know - what I'm asking for requires multiple character arcs, and extra work, but I'd assume building mission levels isn't too hard once the blocks are there, so it's really down to extra work for the writers, actors and ainmators. But you know what, I can't see anyone putting this level of thought and soul into creating these these characters so far not to care about the end experience. I don't even care how much longer we'd have to wait or if they jacked the cost up a litle, if the experience level was to get that much deeper. Heavy Rain is doing choice and consequence very well right now to the point that the game can be an entirly different interpration and experience, and I hope that's what we get with ME3. There are a lot of expectations on this game, and I hope (and trust) that Bioware do it right. Don't rush out a game to capitalise on the hype - take the time to make it worth the wait. And we will wait. Some less patiently than others, granted. But I always think the best games are simply ready when they are ready.
When I finish Mass Effect 3, the ultimate test of the story arc/gameplay variety would be if as soon as I take Shepard to her end, I put in ME1 and start from the beginning.