Even on a system with gargantuan I/O performance, VMware could offer an option to introduce write-back caching of VM I/O, including lazy writes, which could boost performance in VMs and reduce I/O load on hardware (e.g., SSD storage on the host system).
Scenario: A VM writes, then overwrites and/or deletes data it uses temporarily. A RAM I/O cache would both speed up the performance of the writes AND ultimately discard data that never really needed to be written to the host system hardware.
It would of course need to be a configurable option, so that folks who are concerned with recovering from failures wouldn't chance losing as much data.
-Noel