I was at an apple OS X seminar a while before OS X Server was released, and they stressed that OS X Server was an entirely new product, and not an upgrade to OS X server 1.2 or ASIP.
The presenter kept making it clear that this is OS X Server version 10.0.X or whatever, and not 2.0. Its an entirely different product.
You can't really upgrade 1.2 or ASIP with this new product. Either way you need to do a reformat and start over.
Do I agree with their logic? Sorta. It's been almost 2 years since 1.2 came out. But yeah it does seem like people are getting screwed slightly.