I believe usage of the KVS tool is not as widespead as that for Expert Flyer.

This is mainly because it is not as convenient to use. For a start E/F can be accessed from almost any internet connection while KVS requires a client to be loaded onto a PC, then gets licensed for that PC only. Also, to effectively employ KVS, one needs a little training as well as awareness of the different reservation systems that may need to be use for different airlines. E/F does this automatically.

These days there are issues around with bucket availability search software, which when taken to it maximum, could be set up to search for and actually book award flights on your behalf while you are otherwise occupied (e.g. Sleeping). This would make it nearly impossible for those who do not have access to such software to book these same awards for hard to get routes/classes.