QM possesses some fundamental level of complexity, but I wouldn't agree in this context that it's "fundamentally complicated".
I see what you mean. It's certainly a good distinction to make, even if it's difficult to articulate. Again, though, I think it's Occam's Razor and induction that makes us prefer the simpler entities-- they aren't the sole inhabitants of the territory by default.
Here's our place to discuss Less Wrong topics that have not appeared in recent posts. Have fun building smaller brains inside of your brains (or not, as you please).