From what I can see on wiki, it was probably a ratings thing. Sucks though. It was definitely getting more interesting, rather than losing steam... and what a cliff hanger... dear lordy!

Dr Rosen was in turns a manipulative bastard and the very clever and caring glue holding his team together and they really got into that in S2. It showed the writers to be very smart the way they were really delving in to all their characters.

So sad to see another good show disappear. :(