There are still long-term benefits, I'm sure you'll agree, with contesting (and winning) in these seats.  Here are two reasons:

1. Nick Lampson might do a fantastic job as a congressman, and develop personal popularity in his district that enables him to keep winning because of his moderate views (a la Jim Matheson, Stephanie Herseth, Dennis Moore, Melissa Bean perhaps).  In this case, the seat may be at least "lean Dem" for the next few cycles or until a big Republican wave (if that ever happens again).

2. Even if Nick wins this time and loses in 2008, by holding that seat, hee has the opportunity to get the Democratic message out to Republican voters who haven't heard it in a long time.  I hold out hope that we can reach voters like these and eventually convince them that Republican policies, er, suck.  At the very least, maybe Nick will show some Republican voters in his district that Democrats can be good leaders, and in the long-term, maybe some of them will give Democratic candidates a second look.