Honestly after all this time, it's still the same 'ol issues.
You guys initially created the Riven system for the purposes of people using the non-meta weapons. I get that the meta is constantly changing, but you did essentially dig your own hole here. At some point you gotta question whether you should keep digging, because this Riven system isn't getting any better imho. I've seen plenty of suggestions on how to fix it throughout the forums. I don't see disposition as your saving grace in the long run.
Also, with removing sentinel rivens, all you did was increase sentinel riven prices. People are still going to want them regardless if they seem lackluster on unveiling. Surely you'll add them to another riven generation pool not related to unveiling. Perhaps a system where you spend certain resources and some credits to choose what sentinel riven you want. Or smash together random rivens at a terminal and you can choose what sentinel riven you want. A lot of different ways you can do it without removing it from the game completely.