I thought about this, but outside of debugging, there really isn't much use for it. The default is to run the filesystem upgrade, so even if we kept it around, it's not like you could roll back. I more included it so QE can save the v1 db and I could see what the data was that produced whatever oddities in v2 they were seeing.

The argument could be made that the same debugging info could be useful to end users, but my guess is that it wouldn't happen much. With the beefy size of the mongo databases, figured it was more prudent to reclaim that space. I'm open for discussing it if you think it'd be a better default.