During this hearing, two points came to my mind, for what they're worth.
The first is that it appears that the Department of Justice is not particularly interested in upholding Constitutional Rights. Its interest is in projecting the current administration's policies in such a way that Constitutional and other legal issues are either avoided or obfuscated. Thus, we have a case such as the First Amendment issue raised (a web site domain was seized for a year) and, of course, the regular chipping away at the Second Amendment. The Constitution places limits on the government - the DoJ, rather than observing those limits, seeks to reduce them. It's probably not fair to just pick on the DoJ in this regard - I suspect that any government agency, from towns to the feds, would rather not be limited by certain Constitutional requirements. But since the DoJ is so closely related to our Constitution, they certainly deserve special scrutiny.
The second is that a lot of noise was made about the ease of purchasing significant numbers of "assault" weapons by individuals. The claim appears to be that all sorts of weapons are going over the border due to significant purchases by straw buyers. Now, if nothing else, Fast and Furious should have provided some data on just how widespread the problem is, given that known straw buyers were doing their thing with ATF blessing. So, just how many straw buyers were there? Not how many straw purchases were made, but just how many straw buyers there were. It seems that nobody has asked that question. I suspect that there were a lot of purchases by a very few people who were already known to be straw buyers or who became known and were allowed to keep buying. I just haven't seen any convincing evidence that straw buyers are flooding the Mexican border with weapons (other than, of course, those sanctioned by the ATF.)