Oh I totally agree mate. Winter tyres are superior, but as I say it depends where you live. In the East of england, we rarely see snow and the sub zero and hovering between 0 - 5 degree typical damp winters we see, good summers work plenty good enough.
The only thing I didn't like about 16" winters was how terrible the cornering and braking were if you got a 10 degree day during winter. Mushy as hell
That probably isn't so much of an issue with 18" sports winters because of the sidewalls, but they're waaaaay too much money!
But yeah, you raise some good points