'The greater good' would, possibly (zero guarantee), temporarily stop the current attack on Ukraine.
I don't see how it would improve Ukrainians day to day life in the long term. They were already struggling with corruption and a series of other issues. On top of which, they'd be ruled by another country whilst dealing with the terrible destruction from this war.
It would also, most likely result in further attempts by Russia to acquire further territories. Moldova would be next in line without a shadow of doubt.
And so on.
So eventually a series of independent democratic countries would simply disappear. Which is wrong. Full stop.
I really do hope Ukraine will receive more solid support, but I can't think how right this moment.
Putin is a text book bully, as others in here have pointed out.
He would always start a disagreement regardless of what anyone says or does.