I don't know the answer, but I'd suspect the following: nobody in storage business cares about what Microsoft is doing beside Microsoft themselves. From storage perspective, supporting Microsoft is always a huge pain. Most of those who do provide support try to limit it to exposing SMB server. I had a misfortune to try to expose iSCSI portal to Windows Server. Luckily, the company was in its relatively early stages where they could decide what things they want to support, and after couple months of struggle they just decided to forget Windows existed.

So, I think, this feature, just like WinFS, and probably ReFS after it, will just end up being cancelled / forgotten. The kind of users who use Windows aren't sophisticated enough to want advanced features from their storage, but support and development of this stuff is costly and demanding in other ways. If they cannot sell this as a separate product that runs independently of Windows, there's no real future for it. The only real future for Windows seems to be Hyper-V, but hypervisors, generally, have very different requirements to their storage than desktops. Simpler in some ways, but more demanding in other ways.

So, bottom line: it probably didn't see any use because the audience wasn't sophisticated enough to want that, and they couldn't sell it to the audience that was sophisticated enough, but was also smart enough not to buy from Microsoft.