He's pointing out that there are a surfeit of things that could exist in the game for immersion, but are rather debilitating to gameplay. For me, driving along the surface and finding these nice convenient outcroppings of uranium was far weirder from a verisimilitude standpoint (and therefore immersion-breaking) than doing orbital scans; both were all sorts of tedious, though. It was always convenient in ME1 how every important thing on a planet's surface could be found in a few minute's drive from a single landing point, and handwaving it as time compression of the same sort as why it doesn't take days or weeks to fly between stars just raises the question of what Shepard is doing playing Magellan on every alien world s/he comes across instead of, you know, saving the galaxy. Besides, immersion could include dying from getting shot by a single bullet with your barrier down, but hardcore mode is not the default for these games for similar reason. On the flip side, the realist component of immersion would also include Shepard sticking to the business of saving the galaxy instead of gallivanting off on sidequests, but if you stripped out all of the sidequests in the game, or even if you shoved them all to the post-game, the fanbase would scream bloody murder. I mean, worse than they already do anyways.
As for ME3, I have no clue. I haven't bought it yet, and I probably won't for a while.
Finally, to address skullpoker's point, ME2 has a toilet. Two of them, in fact.