You'd think Europe and the US would've learned their lesson with WW2 that appeasing an aggressive nation WHO TELLS YOU WHAT THEY WANT does not give the results you're looking for. It's a fundamental misunderstanding of many within modern politics who truly believe there is always room for diplomacy with everyone.
That is simply not the case. What's the phrase, some people just want to watch the world burn? I don't think it's a burning world but some people just want to use their power to accrue more power. And no amount of appeasement (seen as weakness and thus used to accrue more power) or diplomacy (seen as weakness as they use it to delay and to confirm to the diplomats that they are willing to talk while they seize power elsewhere) works with people in these mindsets.
Across Europe, America, and most of the world, nations who don't necessarily always think of using their power for territorial gains believe everybody thinks the same and everybody feels the same. This is simply false. Also, I blame the American thought process concerning diplomacy on the US being a relatively new nation. The US cannot fathom how a nation with a thousand years of history on the same lands feels or thinks. The US cannot fathom how Russians view Ukrainians and the lands of Kiev and the lands that their pagan ancestors fought over and ruled as tribes 1300 years ago feel. And because the US cannot fathom this thought process of TRUE history, the US believes that everybody is okay with the modern nation states and modern borders.
This is so naive, it truly is American.