...or you could say that with less surface area it will get dirty faster, because the rate of crap hasn't changed but the surface area which it needs to cover is smaller
I'm not sure I'd call these engines particularly dirty. You're right though, it's just an engine, and there's no magic going on...stock plugs, stock gap, and with more boost reduce the service interval, the car will run fine.
Yup. Your engine will be perfectly happy with any plug that meets specification.
Further technology really only affects non-performance factors. Pick your compromise and be happy. They all provide benefits, and they all work just fine.
Not a single one of those companies has any mysteriously superior mastery of electromagnetism.