There's a few things he mentioned that were interesting. You can go to
https://old.reddit.com/user/UnderworldOfficial to read all his responses, but here are the ones that stuck out to me:
1) They recognize demand for a physical release of Riverrun
2) The whole of the Experiemental Sound Field '92 was recorded
3) spoke to the more structured feel of 98+ live sets, "Around 2000 audiences changed. What people were listening to shifted as perhaps how they chose their recreationals changed. We transitioned because of audiences from a band that was encouraged to perform long open ended improvs which sometimes were fantastic and sometimes awful. Then around 2000 the mindsends of audiences shifted and we honoured that. It became a new challenge. We have a lot of live recordings that go back decades!"
The "sometimes fantastic and sometimes awful" bit really is key to why they don't do it now.
In another reply he says it's something they've discussed recently and are exploring alternative show settings where improvs would be more appropriate.
4) Rick's idea to put song names on the screen
A decent AMA, but he was only around for about an hour answering questions.