Russia said don't join Nato or we'll destroy you, Ukraine. And then Russia attacks Ukraine anyway. So what would be different if Georgia, Ukraine, and the other smaller democratic survivors of the USSR join NATO? Russia will still want to attack them.
Edit - one more thing, Russia said it threatens us if NATO is right next door to us in Ukraine. So Russia wants to take over Ukraine, and they'll be right next door to NATO in Poland. They were already right next door to NATO.