EM toxicity isn't just from cell phone towers. It's from any electrical device anywhere near you. Whether you're in a capsule floating through space, or in a base on Mars, they're effectively the same thing.
We evolved specifically for Earth's conditions. Alter those conditions or take us out of them all together, and the result is sickness.
And the claim that "we evolved for Earth's conditions" may be incorrect as well, since the theory of evolution is full of holes that you are probably aware of.
...the fact that you can ask that question in a serious manner suggests to me that you have an identification with the idea of space travel that prevents you from taking a step back and just trying on different thinking. I'm not suggesting that you're absolutely wrong, or that I'm seeing things clearly and you're not. I'm just highlighting what looks to me like a rigidity to your thinking, and I'm trying to present you with counter-ideas and highlight potential problems.
But we're not talking about flying in planes for a few hours. We're talking about living for extended periods of time in space, in a hermetically sealed Faraday cage, with no day and night, surrounded by and trapped with electronic systems that are giving off constant EMFs.
There's lots of other arguments against the idea of colonising other planets and moons. We haven't even touched on the simple idea that the billions of dollars it would cost could be put to infinitely better uses down here on Earth.
So to sum up, I also see space exploration or even colonies elsewhere as a relatively neutral activity that can be used by both STO and STS - similar to flying airplanes. There are advantages to it - some of which we might not even be aware of yet - and there are disadvantages, some of which you outlined.