The reason that people are joining NATO is because they are afraid of Russia and want protection that Putin and his croniest regime can't provide because they themselves are a threat and they also do not keep any promises like in cases of recent Armenian conflict has shown.
If Estonia, Georgia or Ukraine were not afraid of Russia and had guarantees that Russia is a sane power that respect rule of law then NATO would not be needed. But that is not the case. Russia is a threat so the countries on its borders need to join NATO to be safe. It is cause and effect and anybody with a brain understands that Russia threat came first compared to Nato bases on Russian borders.
TLDR: If Russia stops threatening in neighbours militarily and politically then it will have less NATO bases on its borders.
Yours is a good case for why nations may wanna join Nato. But there is still a Russian case for why Russia may not want Nato on its borders. When I say Russian, I mean Russian. Putin is not Russia, nor is a given that Putin is not in fact pursuing a foreign policy that is in line with what Russians will like to support.
Are Russians supposed to forget their history? Does once bitten, twice shy not hold anymore? And Russians have been bitten not just once, but many times, by a few notorious pillars of Nato. But, another may say, this is a new Nato: meek, mild and defense only. Is a Russian not well advised to heed the admonition that a tiger cannot change its stripes, nor the leopard its spots?
Let us take a look at a notorious pillar of Nato with a long list of past aggressions on Russia. Deutschland! A notorious aggressor. A first class predator. Another leopard who purpots to have changed its colours, and whom Russians are to let down their guards when it approaches! Last Century alone Germans assaulted Russia twice. Russia was brought down to its knees the first time and collapsed. The second time, Russia did not collapse, but the butcher's bill was huge. Close to some twenty millions.
And what of John Bull? Another notorious Imperialist. A first class predator. John Bull has tangled with someone or other on all shores of the seven seas, as well as on the seas. Russians, except those of extremely short memories, recall that John Bull has tangled with Russians in Crimea, as well as Afghanistan.
And France? Was it not from France that Little Boney sallied forth in a campaign that took him all the way to Moscow?
It may very well be that these predators truly changed their stripes and became lambs in Nato, but is Russia supposed to let its guards down? What if the supposedly meek and mild Nato of today suddenly becomes hostile and aggressive tomorrow? A Russian has to guard against that.
Keeping hostile military alliances far from one's frontiers is a wise policy. It is a policy that has been used in the past by the US in the Monroe doctrine. And if there has been any constant in John Bull's foreign policy over the centuries, it has been to always foil any one nation or military alliance to dominate the continent.
Why should Russians not learn from John Bull and adopt the wise policy of not allowing any one military alliance to dominate the continent?