The idea that old software is inherently better is bogus. Software doesn't age like a fine wine. Unless a software project is completely hosed new versions are less buggy than old versions. Regressions happen, but they should be rare.
It's also worth remembering that even in the case of the worst bugs possible that completely break the network, you can issue another auto update that fixes things again. It's only if you break the software and the update mechanism simultaneously that problems start.
Bitcoin is a system where people need to upgrade from time to time for the good of the network, this is especially true for people who are mining or who could benefit from upgraded security features. Auto update is absolutely essential for these people.
the argument for not auto updating is that it gives a higher diversity in the network, which i think is good.
in my opinion does more diversity mean harder to attack, and new bugs have less impact.
that was theymos's point too.
people who mine or need security features, would naturally keep themselfs updated, they don't need auto-update, they are tech people.
