I think Otto's an incredibly useful feature, and I was one of those that screamed bloody murder when the idea was first floated. Leaving that all behind us, I think that Otto deserves special configs/options.
#1. With Otto enabled, "fix broken links" ought to be disabled by default, if it's not already. I don't know if it is already or I just have myself to blame (again), but with Otto on your broken links will be Ottoed the heck ought of there ithin 30 seconds, and long before you realize what's happening. And then of course the library gets Otto-saved, and you are up the creek.
#2. Now that Otto's moved in for good (presumably), MC fully enters the age of removable media. I know that the Elite among us have been doing it for a while already, but with Otto it's so simple an idiot can do it, as I've already verified. The only missing piece to the puzzle is enabling your MC view to ignore missing files (and not delete them). Marko came to the rescue for me with this expression:
if(IsMissing([Filename]),no,yes)
. . . but this really could be incorporated into MC by default, couldn't it?