Yeah they definitely increase re-watch value. I enjoyed the director/writer commentaries too, gives you appreciation for more subtle aspects of the episodes. It's sad to have generally lost all those extras in the current streaming landscape 🥲.
I had that same thought about all the lost content with streaming just yesterday! Way back in the day the season sets went on sale for like a few dollars each as part of some promotion at the local big box store so I got a lot of them (they did some shady shit like season 4 & 8 were full price though). I still watch them on that so see all the extras. Maybe I can hunt down the commentary (doesn't start till like season 2 I believe) and try to find a way to link everything for easy viewing.
Haha that is just the way it would be, only some of the seasons on sale 😅.
I don't know how technologically adventurous you are, but I'd recommend using Jellyfin as a library for all for any digital content you might have. It does require setting up a media server, but it's pretty great for managing special features and extras in with the episodes themselves.
Love a Jellyfin recommendation. Been running one for a bit and have some of them on it, servers waiting for me to install 2 new hard drives so I can get the rest of my collections on it lol. I've been a stickler for getting all of the bonus content even the music videos etc on some movies, it gets quite extensive but only having to do it once and having it secured in a second form is nice.