Russia signs treaties with no intention of abiding by them if it feels like it. You well know that the reason why Nato countries are not signing because Russia is in breach of the agreement to withdraw troops from Abkhazia and Transnistria.
What is the sense of a treaty which is signed/ratified only by one side?
Russia is in breach of the agreement to withdraw troops from Abkhazia and Transnistria
Do you remember that 1999 agreement between NATO, Serbia and Russia provided for return of Serbian authority in Kosovo (among other things)?