My take is that the dims did a great job of getting out their vote and republicans simply weren't very motivated. While the WoT is certainly a huge issue that's really the only messages the republicans put out.
In addition I don't know a single person that worked for the party either in 2000, 2002 or 2004 that did so this cycle. Again, while the WoT was a big one it's tough to call up people or walk neighborhoods and get whacked over big government, entitlements and border control. I got killed over the latter in 2004 and while getting bitched at wasn't the only reason I didn't work for the party for the first time in nearly five decades it was a factor. Grass roots get out the vote efforts are huge. The passion wasn't there this time around.
While us political junkies are always going to vote for at least some chunk of voters the vote has to be earned. In my opinion republicans simply didn't earn it this time around.
I read somewhere that in Southern California in Orange county, the heart of the republican belt, only 40% of normal republicans voted.