Being able to conveniently see and search by IP could be a massive time saver. There have been more than a few times were I may only know the IP for various reasons such as getting an activity alert from a firewall. Getting into a machine like that as quick as possible to mitigate or shutdown can be key. Considering cryptowall threats etc. Seconds/minutes count.

To keep the UI clean it could be on by default, or even better maybe having a checkbox in admin tab to turn it on/off.