This would produce discontinuity and vastly different levels of quality from day to day.
Probably. American comics do not maintain a single artist or writer over their entire run, usually, even creator-dominated comics like Neil Gaiman's Sandman rotate all positions (although there were far more artists than writers for Sandman, IIRC), but the turnover tends to be over many issues/months or years, and I imagine their general skill level would be much higher than a LW collective.
People have been asking this question here a lot lately (not sure, why, but still). MoR has been by far the most effective ad for LW so far, but this is a one-man effort. I wonder if a web comic drawn by the regulars based on, say, recent posts and comments would be another way to get people interested. Just to set the bar really, really low, here is my quick impression of this post (the idea is stolen from #lesswrong, but the obvious bad pun is mine):