Yeah, but there's the logistics of team training and pitch preparation for the next games to consider too. I'm almost certain reserve days will have been discussed (as we have them for the semi and the finals) and the fact we don't have them probably suggests they were not feasible. There's a lot of teams moving to a lot of grounds in a pretty compressed time scale (most teams will play 2 games in 3 days at least once and most grounds are hosting 2 matches in 3 days too).
Although that said, I think the main factor may well be not wanting to play World Cup matches in empty stadiums. Ultimately, I think that's deemed to look worse for the sport (whether it actually is or not) than No results.
Perhaps, but I think 1 game per day is generally better. How much interest did Afghanistan v New Zealand get when it clashed with England Bangladesh? Not a lot, and most of what it did get was because England rolled Bangladesh over.