Fair enough, and I can see how it would be beneficial to use flash SANs to cache the vCenter environment as a whole, however it seems logical that you would want to have as an option flash caching at the host level to maximize SSDs that are local to that host instead of requiring implementation of a vSAN (which can be thought of as essentially a RAID of shared disk space where each individual host's shared space can be considered as a member drive) in order to use any host/IO caching. Using vSAN caching it would be possible that you could be caching local IO or host swap with remote flash resources... which would be limited by network bandwidth.
Rather than pointing out the bugs and configuration issues as a reason to discontinue it I would think VMware would focus on refining it to make it easier to use and less buggy, perhaps even considering implementing Virtual Flash Cache as a stand alone ESXi option as single server environments would benefit greatly from it, and cannot, obviously, use a vSAN.