The problem is that baseball, more so than any other sport, relies on consistency and keeping up routines. Having a three game series before the start of the rest of the playoffs would arguably ice the other teams, which is something that I'd prefer to avoid if at all possible. Heck, I think that the delay already is too long for most teams. Couple that with the MLB's postseason schedule already bleeding into November (something that I think should be avoided at all costs), that's just asking for trouble in cold weather cities that don't have domes.
The only way I would conceivably consider having a three game series would be if they did something along the lines of having the first two games be a doubleheader, then playing a third game (if needed) immediately the day after that, and then playing their NLDS/ALDS opponent the very next day after that. That'd be awfully brutal for a wild card team, though. I'd be more okay with that, though. And heck, for ease of scheduling and travel, have the first wild card host all three games.