laws that require all sapient AI to be killed.
Citation please. You need a license to make AIs, yes, and that makes at least some sense. There were AI killings directly in the wake of geth rebellion, yes.BUt I very much would like a quote saying that sapient AIs are required by law to be killed. Especially given that Citadel sent diplomatic ships into geth space on several occasions.
1) It's not really prefferable to have the Reapers just destroy our human populations since that means that they would stop holding back and make things far more difiicult. The main reason the Citadel races were doing as well as they did was because the Reapers weren't trying to just destroy them all since they wanted to catch a significant number of them alive to use to create new Reapers for the harvest. Them having to work to invade cities and take people on planets actually slows them down enough to make things easier for everyone else or else they'd just blitz through by destroying everything that was too hard to take just to capture some people. Indocrination doesn't seem like it would be that bad considering that most people in colonies likely don't know anything that important and we could probably make tech to detect it. Husks are likely probably just going to be an annoyance with our tech advances while we may also be able to come up with anti-huskification tech by way of giving people nanibites like the ones Iron Man used in infinity wars so likely even less of an issue.
2) Again, the Reapers aren't actually interested in causing as much casualties as possible and seem to avoid things that can do long term harm to a planets biosphere and once again most everyone in setting tends to avoid doing that kind of thing. Keeping the shield on isn't even an issue due to free power.
3) You seem to be underestating just what kind of damage a space station could receive and seem to just be calculation the low end of the potential damage. If the damage gets bad enough and during a time of war where the resources that would go into repairing the damage would be better spent elsewhere the governments may just decide to move people to planets than waste resources on fixing space stations
4) Wasn't one of the main complaints from fans in this forum in regards to the Quarians is that they realy should have been able to find a planet. Seriously, we've seen Shepard and his qrew easily survive on Rannoch so that excuse is bullshit. Especially considering that Tali implied that the main reason they don't try as hard to find new planets when they had hundreds of years is becaused a lot of them don't want to wait long for their peoples immune systems to adapt since it would take generations and many keep pushing to try to retake their homeworld instead. The Quarians have been noted by fans to have seriously made some dumb decisions
Also Thane a Drell outright states that even though they could find a planet that is more suited to their people many of them willingly choose to live on the Hanar world out of sheer gratitude. Again, considerin their low population it would take hundreds or even thousands of years to potentially bring a planet to full capacity for them.
5) Intergalactic travel and industry seems like it makes it less of an issue. It also seems like less of an issue since races with space travel have their entire system to gain resources from instead of just a single planet there.
Pretty sure we see Elcor outside of the Citadel in several other places. It should also be noted like Uber pointed out that they may have artificial gravity which may allow them to spend time at those levels just enough to avoid health issues.
The destroamino thing isn't really much an issue anymore thanks to our terraforming package IIRC we can also cure the sydrome for the Drell with a project which should expand their choices signigicantly. Finally I just said that habits are useful for a select people but not really necessary for most with most everyone perfect able to live a high quality of life on a traditional colony world.
1) Reapers will not be "holding back". And yes, the weight of bodies is going to be an issue. Reapers capturing our technology, capturing our infrastructure is worse than them destroying it. And that's assuming it's easy to destroy it. Because, again, a ship in FTL transit is invulnerable. To make a habitat perfectly invulnerable you just need to put it into FTL transit at low velocity (something like 1.00000(0)1 C) with somewhat randomized flight path. Bam! No one can do anything to it.
2) Everyone in the setting avoids doing it because garden worlds are a rare premium. Thus reinforcing my point that space habitats are the logical next step.
3) And you understatement what kind of damage a non-core world colony can sustain.
4) I don't remember those complains, but, even giving this to you, and even conceding drell, we are still left with elcor (require high gravity planets), volus (require high pressure ammonia-based biospheres), hanar (require aquatic planets)
5) Habitats are more optimal, and, in the mass implementation, economic, for everyone, than planets. I fully expect planets to remain the main center of population for the next several centuries, but I also very much want to push for further colonization using space habitats, and to encourage emigration from planets to habitats.