I think I lean towards Kevin Drum's view that the Democrats have been sufficiently ruthless and hypocritical about manipulating the rules of the game to get their agenda passed, against Matt Yglesias's argument that Democrats treat "procedural rules...holy writ to which policy objectives should be subordinated." Drum doesn't mention that Harry Reid and the Dems, while they have not unilaterally changed the filibuster rules, have been aggressive about filing cloture, and fairly aggressive about other manipulations of Senate rules (such as "filling the amendment tree"). And Democrats have been, in my view, fairly creative about loading up bills that were going to pass with lots of policy goodies that might not have otherwise passed -- that's especially the story with both ACA and the stimulus.
One might think that Drum is wrong to raise recess appointments ("Obama has made increasing numbers of recess appointments"??? Well, yes, compared to last year, but not compared to most presidents). However, I think the evidence there is that for whatever reason, the Obama administration just doesn't care very much about executive branch positions. I think that's a mistake, but it doesn't appear to be a mistake caused by overly legalistic respect for the rules, especially since no one thinks that a somewhat higher rate of recess appointments would be at all unusual. The same goes for Senate procedures to overcome holds on those nominations; there, it would in fact take more aggressive "Calvinball" use of the rules, but again there just doesn't seem to be much interest from the White House, as seen both from their silence about it most of the time and from the extremely slow pace of appointments in the first place.
But the real issue is whether Democrats have refrained from filibuster reform because of either a foolish respect for the sanctity of Senate rules or because of a foolish believe that consistency on these questions is more important than passing one's agenda (since after all almost all Senate Dems were pro-filibuster from 1995 through 2006). I really don't think that's it. As I've said before, I think that there are strong incentives in the composition of the Senate and how Senate elections work for individual Senators to fight hard to retain individual influence. And, after all, the same thing basically happened when the GOP was in charge. That surely doesn't make partisan and ideological Democrats very happy, but it's about the nature of the Senate, not about differences between the parties.
I said I lean towards Drum's point of view...but I would say that I think that the Tom DeLay Republicans, or perhaps just DeLay in particular, seemed to be actually different, in that they had an unusually small amount of respect for norms that were previously thought to be in everyone's interest to maintain (such as, for example, waiting until the census to redistrict, or only impeaching presidents for serious matters, or threatening to have a state legislature overturn the results of the presidential vote in that state). In contrast, while I think that Republicans have generally taken the lead in ratcheting things up in the Senate on the way to today's 60 vote requirement on everything, I don't think there was any specific point of discontinuity where I'd say, Aha! That's where norms were violated! The jumps in 1993 and 2008 were real, but at least in my view not quite the same thing.