All this data is potentially out of date, and should be taken with a truckload of salt
These wormholes, although they disappear with time as other wormholes do, are more or less persistent: when a static wormhole collapses, another will re-open somewhere in the system, leading to a different system of same class.
For example, a Class 4 W-Space system can have a static Class 3 wormhole. As soon as the wormhole collapses, another wormhole opens to another Class 3 system.
It can be very profitable to collapse a static wormhole on purpose, opening access to another neighbouring system - and maybe another K-Space exit.
Also, it can be used to get rid of enemy corps on alliances inhabiting that precise system: by collapsing the wormhole you then prevent them from getting into your system, while still having another possible exit from the system.