Nevertheless, it is important to remember that Senators are chosen by their homestate voters, and feel some obligation to be responsive to their views.
What's interesting about the vote, as John Sides of The Monkey Cage pointed out, is that many of bill's opponents came from states with less than majority support for tougher controls.
Note that in every state where a majority favored stricter gun laws at least one of the two senators voted in favor of the assault weapons ban. On the other hand, only 17 of the 74 senators representing states where fewer than 50% of citizens wanted stricter regulations voted in favor of the ban. Also challenging for gun control advocates is the fact that while only 13 of the 50 states had 50% or higher support for stricter gun laws, many of these are the most populous states.The demographic fact is that Senators from less populous states have disproportionate power in the Senate -- and that's the one feature of the Constitution that the Framers forever barred from amendment.
And while I wish at least a handful more Senators showed "courage" and "leadership" -- rather than cowardly followership, the outcome is Constitutionally understandable.
I would also call to your attention Sarah Binder's piece, which shows that the 60-vote requirement in the Unanimous Consent agreement on the bill was a reasonable response to the situation, and even prevented some objectionable conservative amendments from beings adopted.