Kevin Johnson had lower assist totals in college than Billups (4.4 to 5.1) but a much higher assist % in the NBA (38.8 to 28.2). I couldn't find the assist % (the better stat) for college. Lin had only 3.5 assists per game in college and has a higher assist percentage in the pros than Billups (31.6).
I don't think it's so much "shoot first pg" as it is "sg in college too small to play sg in NBA so he has to play pg." I remember some college stars (such as OU's Hollis Price) having no chance in the NBA because they couldn't make this transition. Jimmer Fredette may wind up being the latest casualty.