Hmmm.
You prefer endings like TES where it never really end?
Kind of, but... not really. Morrowind felt 'right' after you finished it, but Oblivion was just so abrupt and in the end, you felt like you'd accomplished nothing, so I didn't like that one bit. Morrowind's success was in the stunning 'believability' of it's game world, to the extent that even when you finished the main quest and were left to do your own thing, you still felt like you were in this unknowingly massive world with untold wealths of things to do and explore. Heck, I STILL get that feeling from Morrowind to this day! Oblivion just never felt right from the start, and the world honestly felt hollow and unrewarding to play in, at least for me.
What I would like is for you to be able to resume playing in the world once you've completed the story, only perhaps with some aesthetic changes. In Mass Effect, they could have just used an altered texture set that would show the Citadel in it's run down burnt out state (heck, just take it as it was in the last mission and remove the fire and explosions and you're set). That way, you're permitted to continue on anything you either missed or forgot to do before the endgame or to just continue exploring the star systems, only the world still reflects what happened. You honestly wouldn't even really need to do much additional voice acting either... Everyone could just have some generic lines that reinforce the success of what you've accomplished.
It wouldn't take much time really to create the smattering of extra content to extend the endgame in such a manner. And we certainly have the technology and 'cinematic drive' to justify doing such things. At least... I think we do.
By contrast, the place with all the Thorians is ridiculously easy for biotic characters, but can be very challenging for soldier characters (especially if you get a little overconfident and run ahead too fast).
I can understand that. While I had pretty powerful weapons and armor at the time, the Thorians were extremely strong and would often overwhelm you with sheer numbers before you could take them out. Unfortunately the AI was, quite frankly, retarded, and would just get stuck on any and every little thing they came across... The Thorians in particular seemed to enjoy just running in circles - so long as you didn't move - awarding you infinite time to take them down. But I did come close to dying a few times while running around in that underground 'lair' on Feros trying to take out that giant 'plant' creature, and having to fight what was probably hundreds of Thorians. That was tough.
I'd love to do a Biotics-centric run but, with ME2 about to come out and my near-total lack of time to play games these days, I just don't think I'll ever get around to it