Also why are all those alien species all comfortable with the same amount of gravity and breathing the same air composition on places where they all mix together, like the Nexus or Citidel? Human astronauts lose muscle mass in space, look at series like the exapanse where they make the guys who live in the asteriod belt long and thin and when they are captured by earth they can be subjected to torture just by exposing them to gravity. Also the Earthers in the series can knock them out with one punch.
Yet in Mass effect all the alien races are as strong as each other basically, all handle 1 G pretty well and breathe the same mix of air despite them all evolving differently on different planets. Only the Quarians are shown different in any other way.
[...] Also what about diseases?
The Expanse is much more of a hard sci-fi setting than MEA, so naturally you expect much more realism. Andromeda is a space fantasy, so you have to let more shit slide, because otherwise they wouldn't be able to tell the story they want to. Like the whole colonisation thing: not possible in the way described in this game. Even if people found a second Earth with perfect gravitational and atmospheric conditions, they wouldn't just be able to land on it and start copulating, because the moment they breathed the air, they'd be doomed. Microorganisms would kill them all within hours, days at most.
It all comes down to expectations - the authors or creators shouldn't ask you to manage them. You shouldn't be required to suspend your disbelief in order to find a fantasy world credible. Tolkien believed that in order to create a good setting one needs to achieve "the inner consistency of reality". He went on to explain that it's easy to say the sun is green. The tough part is to construct a secondary world in which the green sun is perfectly credible. And that's where Bioware fails miserably.
Of course, what Tolkien describes is an ideal. A goal for every creator of "secondary words" to strive towards. And it becomes more difficult the more fantastical the creation is. The audience can evaluate those worlds, based on how close they get to that ideal. Of all the games I played, I think Planescape Torment guys did the best job in that regard. The setting was ridiculous, but I never questioned its credibility. I might also be idealising, because I last played this game over a decade ago.