Is very important to know if a equipment is alive, typically a low cost managed switch has not implement SNMP, but sure you can send ping. With the implementation of the PING, we will know the status of the infrastructure, so easy way to diagnostic it.
I think this is a good idea :)
ICMP ping from Java is not a straightforward thing to do.
There are lots of programs that are designed to track uptime of hosts like cacti, nagios and open nms that might be more suited than mango for tracking uptime.
Or as you say get a slightly less barebones switch which has SNMP.