^ This.
I won't deny I also find Jb Minecraft a bit of a dull map, however at the same time it's a popular one that has brought in lots of players operating 24/7. It'd be risky to add map rotations to these servers. Our only Jailbreak server that has a map rotation and regularly exceeds 24 players* is LA Jailbreak. On the other hand, UK Jailbreak, a former 24/7 Minecraft server turned map rotation barely breaks that limit.* Let's also consider NY Jailbreak and Jailbreak Custom (EU), both 24/7 Minecraft servers and both of which regularly break 24 players.*
* = According to gametracker.com player numbers data within the last 30 days.