I don't even know why you want to based on a country just to launch a ICO when you can still internationally promote it to there.
Maybe it is because Switzerland is a rich country that can also be one basis of some investors?
I don't think because if the rich country,even if it is rich country the population is less so we can't expect more cap values from the investors on a particular country.Basically the wealth of a country will be based on GPA still it doen't means that country has the most currency,it simply means they have less population.I think the reason maybe tax and regulations will be favor for crypto currencies.