I think its more an issue with game design than it is with how big it
actually is. Like you don't need infinitely generated worlds to produce a sense of scale, you just need it to take time to explore, and a good reason to explore. And this is ME's greatest failure I think: You can't interact with anything. You skip around space instantaneously, so the largest thing in the game is the citadel.. it's the only object that takes any amount of time to actually traverse (that, and planets, which you don't really
want to explore). Yet you jump around that too, and are only actually interacting with preset objects.
The problem I think is that there's nothing to interact with. And there's no interesting ways to interact with the things you can interact with. Like star control 2 is technically a small game, and a small world; it just feels big, because it actually requires time to traverse, and there's actually things to find. Zelda games tend to be even smaller (primarily a sequence of small rooms), and yet feel much larger. Again, time, secrets and interest play a large role in why it feels that way.
people try to use procedural generation as a crutch, to avoid actual game design (see: no man's sky, minecraft; note the latter is popular by accident, adventure mode was intended as the primary, but loses its appeal quickly. Creative mode became the primary appeal by accident.) but its simply not sufficient without giving a compelling reason to actually explore and interact with the map.