Not OP, but I do single-region us-east-1 for a few reasons:

1. The severity and frequency of us-east-1 outages are vastly overstated. It's fine. These us-east-1 outages almost never affect us. This one didn't; not even our instances in the affected AZ. Only that recent IAM outage affected us a little bit, and it affected every other region, too, since IAM's control plane is centrally hosted in us-east-1. Everybody's uptime depends on us-east-1.

2. We're physically close to us-east-1 and have Direct Connect. We're 1 millisecond away from us-east-1. It would be silly to connect to us-east-1 and then take a latency hit and pay cross-region data transfer cost on all traffic to hop over to another region. That would only make sense if we were in both regions, and that is not worth the cost given #1. If we only have a single region, it has to be us-east-1.

3. us-east-1 gets new features first. New AWS features are relevant to us with shocking regularity, and we get it as soon as it's announced.

4. OP is right about the safety in numbers. Our service isn't life-or-death; nobody will die if we're down, so it's just a matter of whether they're upset. When there is a us-east-1 outage, it's headline news and I can link the news report to anyone who asks. That genuinely absolves us every time. When we're down, everybody else is down, too.