#2: There are regulatory issues for most biotech startups. This means you may need 3 years of cash to burn before you have a chance of seeing revenue.
#3: Startup costs are all around higher. Just about always, biotech startups need specialized high end lab equipment in very specific lab spaces. The only lab I've found that will take me is in San Jose and is $3,000 a month. The _only_ commercial lab space in Pittsburgh is with a state sponsored institutional investor and they only give space to portfolio companies.
A YC for biotech would need to be a true incubator with office/lab space. And you'd have to give each team $100,000. In biotech, $100,000 is equivalent to the "living expenses only" money that YC gives out.
It could very well work and I'd love to see it but someone would have to put up a very, very large amount of capital for something very risky by the standards of biotech investment.
It also gives me a pathway to this: http://news.ycombinator.com/comments?id=13464