1)Pull the majority along as far as we can
Cynically use "bipartisianship" and the honesty and good will of the senate republicans to senselessly investigate a lot of nothing.
2)Our additional views will also, among other things, castigate the majority for seeking to limit the scope of the inquiry
The democrats have already decided, that regardless of the facts, they will castigate the republicans for something.
3)We can pull the trigger on an independent investigation at any time-- but we can only do so once.
The democrats are going to continue to investigate even if there is nothing to investigate. Plus, they feel the proper timing for an "independent" investigation is a few months before the 2004 election.
Yes, politics is a dirty business. But in the past, politics was supposed to stop on national security issues and the Senate intellegence committee in particular was supposed to be relatively non partisan.