You make some great points. I think the US is as much to blame as the Euros however. We have complained for years that the euros were not holding up their end, but we never did anything tangible. Many US policymakers are probably quite happy with the status quo in fact. They like having europe dependent on us.
We also exacerbated the problem by pushing NATO expansion into former Soviet satellite states. It was reckless and needlessly provocative. Are we really prepared to go to war with Russia over Estonia?
Our whole international policy is bizzarely upside down. We tolerate all kinds of economic aggression, deferring to euro-dominated groups like the WTO. At the same time, we go around searching for regional or single country disputes to meddle in.
Depressingly, the leaders of both parties vie to see who can push this failed neo-con policy the hardest.
Let's say NATO wouldn't have included Baltics and Central Europe and in that scenario it would've been a question of time until Russia re-created the Soviet Union territorially. Do you think a modern Soviet Union type organization with 250+ million people wouldn't have eventually swallowed up Germany, France and the whole of continental Europe? In this scenario UK doesn't stand a chance either. Now you have by far the most powerful union on the planet that ranges from northern Japan to West African islands. This is exactly what the US doesn't want - a more powerful aggressive enemy. You need to think beyond A and B here. Russia isn't a country that will stop expanding, the desire to expand its border is deeply routed into their culture, even if it means a significantly lower standard of living.
As of now, Western Europe is incredibly weak and will continue to weaken until a power vacuum appears and an Ukraine-like scenario happens. While UK, France and Germany bicker over details, Russia marches slowly forward. This is my view for the upcoming decades.