To be fair they did, to an extent:
I’m sure it’s not exhaustive, and it doesn’t include all the bullet-points in which you’re specifically interested, but they did provide at least a portion of their roadmap which should be interesting to personal media users. (I’m personally interested in IPv6 support.)
Also, I’m not trying to dismiss your point that Plex could garner some goodwill by providing some additional roadmap info. I’m just not sure everyone read past the “price is increasing” part of the announcement.