Fix the spacing. Keep what you said you would keep.
You said this forced move to the New Yahoo Mail would keep my inbox spacing preferences from Classic Yahoo Mail. It did not. There is more space between lines in the inbox list. You also said there would be a setting for inbox spacing. There is not.. If this line spacing change is because of the addition of logos/avatars, maybe there needs to be a way to turn those off.
There is also more spacing between lines in the folder list, so I can't see as many at once.
Both side panels are wider, wasting space on the screen.
You say "Compact View - Small, Medium and Large views", (whatever that means), "are coming soon!" It sounds like it may the kind of thing that should have been in place before forcing anybody into in a permanent change that they can't revert. If it refers to the inbox list line spacing, it definitely should have been done first.
I really would like to be able to revert until this is fixed.