I agree that it would be a good change
1.7 is like what, 6 years old now? Lol
Even 1.12.2 would be a massive upgrade at this point
But then is the issue with KitPvP.
They would have to make KitPvP the same way Hypixel is (have KitPvP running on 1.8 mechanics and let clients from 1.8 to 1.15.2 join (no sword cooldown, etc. because 1.9 pvp is centered around pve and not pvp and therefore it is trash) with mods or people would be really upset. If you wanted to join survival or skyblock you would have to with 1.15.2 (where the new stuff would actually be used) then you would have to be on the newer version.
Or they could just switch to 1.15.2 entirely and make kitpvp an entirely different server running on 1.8.9.
But that would not be ideal.
And there is also the issue of updating/finding new plugins for the server.
Idk
Hope my opinion kinda helps