Yeah, Russia has no real reason to be concerned about a potentially hostile army being able to stage operations from their immediate west, certainly no experience at all with that sort of thing.
Don't interpret this post as some kind of Putin boosting. I couldn't really care much less about Russia's kleptocratic oligarchs (or are they oligarchic kleptocrats?). But it's pretty simple. Defense policy coming out of Moscow has been obsessed with making sure no army can ever roll across their border from the west, ever, often to the point of outright paranoia. The USA rattling sabers at them every so often (e.g. US Democrats going into hysterics and claiming Russia committed an "act of war" in the 2016 election) or hinting at regime change operations (Bush admin did this) makes them more paranoid, not less.
It's not about Putin being a "good guy" or a "bad guy." It's straightforward self-interest for them to want NATO to keep as far away from their border as possible.