They don't want it over quickly, but they want it over in enough time for them to remain interested in it. The World Cup would have been too long even if the standard of cricket had been higher. Any tournament that lasts two months is clearly too long - the media, the general public (not huge cricket fans, but people with a passing interest) can't stomach that much. The whole affair becomes less of a spectacle (like the Twenty20 was) and more of an everyday occurence. There was nothing special about World Cup cricket in the end, as opposed to the football World Cup, which has a real atmosphere around it - there is little boredom.
If this is so - and personally (though obviously I fall into the "huge cricket fan" spectrum you speak of) I don't feel it is - that's all the more reason to have the preliminary group-stages staged, say, 6 months previously - who knows, maybe even in somewhere different to the tournament proper - and have the authentic Cup start with the Super Eights. Have a qualifying stage (the ICC Trophy) for non-ODI-standard sides, then a qualifying stage where the little boys mix with the big, then a Cup. This would be an even better reason not to give games involving substandard sides ODI-status, had the stupid decision to give 8 undeserving sides ODI-status not already been taken.
And hopefully, next time, things will go as you aim them to go, with the best 8 teams qualifying for the Super Eights.
I don't see any reason to change the one-match-a-day idea (it's what works best for TV, and like it or not TV is the biggest reason we can even have a decent World Cup), and I like the Super Eight format for as long as we have 8 ODI-standard sides (this obviously depends on Bangladesh's progress in the next couple of years - if they become ODI-standard in that time it's a much more difficult question). I think the forumla is OK, basically - possibly it just needs three stages rather than two.
On the subject, my Dad mentioned recently, while watching the rugby, that football is the only major sport around the world that seems to have found the best format for its World Cup. I argued that this was because the gulf in class between the worst team and the best team in football is much smaller than in cricket and in rugby (any team in Germany 2006 could have quite conceivably beaten any other). Can cricket ever have a satisfactory structure to the World Cup?
I think it already did - most people acknowledged the structures of 1975, 1979, 1983, 1992 and 2007 as top-class (and possibly 1987 too, I'm not sure). Heck, even the 1999 one had its merits, though it also decidedly had its downpoints.
As tournaments expand, though, new formats have to be devised - and sadly, they're not always going to work as well as planned even if they are good ideas.