Because on one of these days some big company (hint: where are the ex Bell Labsers working with a very much Plan 9 / inferno / Limbo insipired new programming language) adopts the Plan 9 / Inferno in a a more or less varied incarnation. I could imagine Android having a new kernel not tied to Java only, and supporting a rich ecosystem of distributed 9P objects...
It is going to be big. It does not have to be Google. Someone will do it. I hope. Wish. Dream.
In the end I can't make up my mind, about what is the single greatest idea in the Plan 9 culture. But if pressed I suggest it is 9P and the idea, that we really do not need protocols above the network layer, but HTTP, SMTP, DNS, SOAP, IIOP, IMAP, IRC, SSH, SSL, TP, SNMP and hundred others can all be replaced by "remote file access". And at the same time with file system union directories you can also "inherit" and "augment" any of the "services". This essentially gioves you distributed objects (with natural persistence option). And this all can be done securely with authenticator handles and the Factotum agent. It is safe enough to be run over the public internet.