To this day I don't know what's stopping these streaming services from recreating a bit of the dvd experience and offering to show you some of that was pretty standard at the end (e.g. deleted scenes, bloopers, director/cast interviews)
They want you to spend more time on their platform, right? Seems like there would be a pretty obvious user journey from just watching a film to watching related content about it
Though that still wouldn't bring back something I feel like I'm in a bit of a niche for missing: DVD menus. For about 10 years, we had these crazy bespoke interactive experiences for every single release, some of which went to extensive levels to add in Easter eggs or games. When blu-rays came along, I don't think I remember a single Blu-ray that didn't use a standardised looking menu with basically the movie poster art as a background (I think any variance was down to each studio using slightly different art assets).