That's the only reason I use them. Since .am (Armenia) allows anyone to register a domain I can have boreh.am and hence be d@boreh.am. Still haven't got around to putting up content at the web site at http://d.boreh.am :(
The incident was far from minor IMO. I think .io has had 6+ hours of downtime (full or partial/non-trivial) this year, long enough to push the annual availability down to 99.93% from what I recall from memory of reading post-mortems.
That was enough to spur us to begin planning to move production traffic off our .io domain as well.
Did any of the large TLDs (.com/.net/.de/.fr/.co.uk) have an outage like that in the last decade?
Not being available for several hours can severely damage businesses. Startups that haven't built trust yet as well as some large companies. Imagine a bank's website not being available for several hours. It doesn't matter if it's a DNS issue, people would start panicking very quickly.
Simple vanity.