So should Russia be obliged to pay for transit and provide gas to Ukraine? Why wouldn't Ukraine pursue gas supplies from other sources? It had at least 8 years for that, but all the time was spent on opposing NS2.
"that was unwise" is a simplification, not a proper explanation. Russia is a cheap resource supplier, so it was beneficial for European countries to leverage it for their economy to be more competitive with US at least.
Saudi Arabia has its own bunch of issues with democracy (there is none, imagine), human rights (surprise), a war with neighbouring Yemen (sounds familiar?), but for some magical reason no one cares and alienates Saudi Arabia, and everyone is very forgetful and blind about their issues and doesn't interfere.
People's thoughts are literally tunnelled.
For comparison, consider Iraq's attempt to annex Kuwait in the 90s. The world absolutely considered it a five-alarm fire, with the West immediately planning for war and even China and the Soviet Union authorizing a retaliatory blockade. Most people genuinely and strongly feel that the return of territorial conquest as a common practice would be a disaster for the world.
As I understand it, most of the gas that would be delivered via NS2 would be the gas that wouldn't be delivered through Belarus/Ukraine (depriving them of transit revenue and providing more options for Russia to employ gas politics on its western flank). It rather seems to me that, far from being natural in a world without geopolitical drama, much of its purpose is actually to enable geopolitical drama.
And, of course, the main thrust of the argumentation against NS2 was that it was causing Germany to pursue an economic dependency on Russia that was unwise, given Russia's already-demonstrated penchant for using that economic dependency as a lever in global affairs. NS2 died when Russia's invasion of Ukraine demonstrated the lack of wisdom in pursuing economic dependency on Russia (compounded by Russia withholding gas flows to make Europe came back begging to Mother Russia).