Worth is something only you can say. Is your current performance not satisfactory?
Side by side, the 8600K is much stronger and has 2 more cores and threads, performing better in games and editing/streaming...
http://cpu.userbenchmark.com/Compare/Intel-Core-i5-8600K-vs-Intel-Core-i5-7400/3941vs3886
So, yeah, it is a worth upgrading, but you WILL have to get a Z370 mobo + Cooler as well with the new CPU since your current parts aren't compatible with the new rig.