Hello,
I am also very annoyed this feature disappeared. It should be great you envisage to re-introduce it, especially because the choice "ask me" is still visible as an option (visible and not active, it is why I decided to visit this forum). I never had "a long chain of snapshots", the VM slow down is not a problem for me : I regularly delete the old snapshots when I decide to create a new one, sometime 3 times per day, sometime 1 time per week....