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.