The reserve list isn't going to change. It is more complex than changing names on a list.
If Wizards wanted to fix the issue of Legacy being cost prohibitive, they would just change the banned list for Legacy by adding the reserve list.
High second hand market prices are good for Wizards, the high prices for Legacy are a player problem. It is good for Wizards and not an issue for them. Players don't quickly leave a format/game when they have invested so much into it.