Russia is not in the EU because of fundamental geopolitical differences and diverging interests. Changing the Russian government does not change these aspects.

The same goes for China, for instance. It is naive to think that a democratic government in China would fundamentally change anything to the geopolitical situation or China's international policy and goals.

The government's leanings may influence the means by which a country pursues its geopolitical interests but do not change those interests. Just observe the US.