$150,000 will allow the startup to hire 1 or 2 engineers in the short-term. Is that the real use of the $150,000?
What other expenses do they spend good money on?
Another way to look at this question: If you were a new startup in YC, what would you spend the 150,000 on?
At Demo Day, the investors will know that all the startups have some cash to last after YC, so that they don't have to rush on the first investor that comes along which should translate to better terms for the founders. Or it could just allow them to look for investors a bit later on, hopefully providing them with a better negotiating position by having a product further along or gain some traction before needing the money.
Or do you want the designers to build the blackberry app?
I think spending it on swag would be a horrible idea. I can't think of any company that succeeded because they had really great swag in the early months.
This could open YC to entrepreneurs who can't live on ramen because they have families.