Thanks for the kind words - I almost always try to keep everything separate, and think through the failover scenarios. Power, network connectivity, etc.
In this case, though, we thought about it briefly early on, but it kept getting pushed down the priority list. As a community we talk a bunch about technical debt, but there's ops debt too that I made the mistake of de-prioritizing.
Email's an especially good point - I suspect email's a pretty huge SPOF for all of us. A major gapps outage would be pretty disastrous.