I agree. Given that STM is used to monitor/profile some considerable enterprise environments, it would make sense that STM is capable of an equivalent level of High Availability (HA).
Some options outside of STM providing the HA itself would be to use a VM in a management cell/cluster with DR fail-over via something like SRM. Alternatives could include a cold-standby based on frequent backups or MySQL replication. IP address failover would also need to be accounted for (either by maunual/automated address failover, or smarter agents).
However, those options all work around STM. It would be good for STM to be self sufficient in a HA capacity, or at least have a Solarwinds supported "best practice" HA how-to guide.
Here is a Feature Request for this (via Thwack): FEATURE REQUEST - Failover operation of STM server