Why is the plight of the Ukrainian people seeming more important than that of the Kurds, Palestinians or Yemeni people?

Morally, it's not. Politically, I suppose because Ukraine is an extant sovereign nation being invaded by a wanna-be-again superpower and the similarities in Putin's reasoning echo Hitler's reasons for invading Austria, Poland, etc., etc. Also possibly because of the sheer numbers involved, with 40 million Ukrainians in the Largest nations in Europe.