With that said it isn't FREE: there are taxes and so forth though I believe private US health insurance (like you would be purchasing) is anything from 2-5 times more expensive (my NI contribution on a £33K salary is £130 a month - of which a percentage goes to healthcare - I estimate around £80).
However one big advantage IMO is that the National Insurance Tax is recovered in a standard way by the tax man and there is no tiers or anything - it just covers everything - meaning less stress finding a good deal and ensuring you have adequate deals (I know just ensuring my car is a pain in the bum :) I cant imagine medical!)
The crux being: I dont think it's quite possible to claim it would encourage more startups. But I suspect it would remove another hurdle from any other prospective startups.
I've come to the belief that the lack of universal care in the U.S. keeps workers from being less mobile and from taking risks.
Today I am about 150 miles away from home in city Ive not been to before and my tooth filling collapsed. I went to a random dentist this morning and he saw me within 10 minutes (the time it took to request my medical history from NHS records) and my tooth is now fine! There was no questions about insurance, cost or whatever it's all just simple :D
"Risk taking" is, in my opinion, relatively independent of cost or administrative overhead. Some people would simply not start up any company even when the break even analysis is good. Whereas others would jump on a given opportunity, taking the risk that he / she can do better than the break even analysis.