What is the deal with all these big 19 and 20 inch wheels on roadsters and coupes?

[Perfectlap]

Is this just an issue with 'high end' (as in price not performance) sports cars?

I remember going through hell trying to find 16" BBS RK's for Miata. I would get these blank stares at most speed shops when I told them I did NOT want "big rims". I wonder if BBS even make any wheels that small anymore.

The more I think about it the less sense this makes. The Boxster Spyder has 19" wheels and seems to be the best performing Porsche per dollar but eventually cowl shake will catch up to any ageing car and the rattles and jarring only build on themselves.