We already know that the US Senate failed to pass the recent defense appropriations bill. Defeated by filibuster, the Republicans were joined by two Democrats, effectively killing "Don't Ask, Don't Tell" (DADT) repeal and the "DREAM" act in one side-pocket carom. From what I am able to gather, no one expected any different outcome.
So why try passing it at all?
Well, politics. Duh. Defense bills tend to be popular and politicians generally lose no votes by supporting them. In fact, they usually benefit, since defense bills tend to be larded up with pork of all kinds. Given that basic popularity - surprise! - legislation is often attached to them that is only tangentially (if that) relevant to the main purpose of the bill.
Such was the case here. DADT deserves specific, open debate, preferably after the completion of the military review of the policy. If there is no reason to continue it (and, frankly, I can see none), then the policy deserves an up and down vote, independent of other considerations, putting everyone on the record of approving or opposing it. Which is part of the reason it was attached to the defense apporpriation. Politicians love wiggle room.
As for the DREAM act, that was Harry Reid in full pander mode. For a solid year, Democrats held an absolute majority. They literally could have passed anything, and in some instances, did, without any Republican votes at all. If they had wanted to pass immigration reform (read "amnesty") they could have. And they chose not to, because, other than with the specific, affected demographic group, the issue is not a political winner nationwide. But by bringing DREAM up for a vote, even in the form it arrived, Democrats hoped to ignite some sense of urgency in one of their key voting constituencies. It may even work. But it was breathtakingly cynical, even for Washington.
In the end, both sides got fodder for their political ads this fall. And the rest of us got another dose of realpolitik.