Please can you put it back?
It didn't clutter the UI, it was just couple of menu entries in a menu that is still there and now has just four entries..
If you feel that more than four entries in a menu is undesirable then you could remove three
of the existing entries are they are now redundant, being also now ever-visible to the right
of the contacts.
This feature was very useful for me as collapsing all groups made it far easier to locate the specific group I wanted.
By contrast, in the expanded state that group is just another tree in a forest of items.
I find it impossible to understand how anyone thought it a good idea to remove this feature.