Ed Kilgore explains:
Think about it. Since 1998, we've witnessed the first presidential impeachment since the 1860s, the first presidential election to go into "overtime" since the 1870s; the first attack on the continental United States since 1812; the first major preemptive "war of choice" in U.S. history; and the first televised destruction of an American city. I don't mean to equate any of these non-9/11 occurances with what we witnessed that day, but it has been an extraordinary span of time.
If you want to truly understand why Democrats (especially those whose entire formative political experience has been the last decade) are so often "angry," remember the behavior of the leadership of the Republican Party in all of the non-9/11 events I've mentioned. And then remember what the president and vice president have done to destroy the national unity and worldwide symphathy this country enjoyed just after 9/11, typically viewing domestic unity and global approval with ill-disguised contempt.
I only hope that Ed can appreciate that part of the reason there's a lot of anger also directed at a somewhat nebulous "Democratic establishment" is precisely a perception that at just these moments of conservative perfidy to which he points, the response mounted by said establishment was notably ineffectual.