They did it at the expense of millions of bodies, restricted freedoms and ignoring the voice of native peoples. The relocation of millions of people from their native lands caused many deaths. The world wanted the CIS broken up because it was the USSR.
Russia offers to help them now and if they reject the help it's not like we will invade them. We don't want to be a big empire again. Without the USSR, those countries simply would have stopped existing just like they are now. People might know Uzbekistan or Kyrgizstan but how many know where they are and what they are?
As for those immigrants.... there is a reason they left Russia.. that's all I have to say about it.
The offer to help is at a price some are not willing to pay. The Ukraine for example, does -not- want to be a part of Russia. The lease on the Black Sea port will run out, what will Russia do when it stands to loose that port?
Without Russia, those countries would be different, possible better or worse. They are in Central Asia and have large oil and natural gas reserves. One of them has the Russian spaceport in it. I can imagine the fit Russia would pitch if they lost that. You say that Russia doesn't want to be an empire again, yet the world is seing Putin as trying to ressurrect the USSR.
The immigrants left Russia for several reasons. 1, they wanted to live. 2, they wished to improve their lives. Living under the conditions of enforced servitude. 3, they wished to be free of an oppressive government, whether of the Czars or the USSR.
Stalin did -wonderous- things, but at an awful cost in shattered human lives. Over all, Stalin's evils overwhelm his hero- status.