If I remember correctly, a good chunk of the online demo period before the release of the game was for people who pre-ordered. Even then, I wasn't exactly overflowing with free time at that point (or most points).
Truth be told, I was mildy curious about the game because I liked HL2 and all the other HL2-related stuff. However, I wasn't curious enough to keep constant tabs on the status of the game in the hopes of catching the one weekend where I can check it out.
As far as "wasting dedicated servers" goes, I'd think that it'd be considered part of marketing the game, which is the whole point of a demo in the first place, right? I've played countless PC demos that had some form of multiplayer enabled, so I don't understand why it's somehow difficult for this game to have one.