I love it when smart people accidentally accept a Republican talking point that the Democratic campaigns are cult-like.
All due respect to HTML Mencken, whose stuff I read every day, but to suggest that either Democratic candidate is "just another politician" is really a little too cynical and aloof. Yeah, they're politicians, but they're politicians who will represent America on the world stage; they will represent "our" era in history, and, to that point, they represent an opportunity for our generation to erase a massive skidmark on the American narrative.
The enthusiasm, I believe, comes from a desire to solve this mess -- it's a crucially important moment in an on-going process that has already included thousands of hours working for Ned Lamont; battling the Republicans on FISA; ending the war; watchdogging the Bush administration, and blogging our brains out during this interminably dark ride. No-one believes the sky will open and everything will change in one moment or with one speech. No-one believes this will happen with a one grand slam home run in November. But it's a really big step towards rolling out of this darkness.