YC isn't accepting anything; YC startups are accepting the investment. Pg addressed this in another thread [1].
It is quite obvious that, assuming your desire is to quickly scale your startup, $10-20k isn't enough. That's why YC has always had demo day, the goal of which is to secure investment. Even still, that day will remain important; Yuri didn't change that.
As an answer to your second line of questioning: Have you ever considered the cash value of "free" resources offered to YC companies? YC could just invest a lot of money, or they could provide mentorship opportunities and resources. They chose the latter (obviously), and have had clear success in doing so.
It is quite obvious that, assuming your desire is to quickly scale your startup, $10-20k isn't enough. That's why YC has always had demo day, the goal of which is to secure investment. Even still, that day will remain important; Yuri didn't change that.
As an answer to your second line of questioning: Have you ever considered the cash value of "free" resources offered to YC companies? YC could just invest a lot of money, or they could provide mentorship opportunities and resources. They chose the latter (obviously), and have had clear success in doing so.
[1] http://news.ycombinator.com/item?id=2156560\
[edit] Haha... three other posts in the time it took me to find pg's response...