Europe did the right thing by resizing the big and powerful territories as well as settling conflicts between countries. With the emergence of alliances, countries will feel safer due to the protection as well as cooperation demanded by alliances. Due to this, the entirety of Europe was locked in a stalemate which brought a period of peace with it.
The peace talks and prosperity offered by the Congress of Vienna were worth the possibility of making a small war into something huge. Reorganization was direly needed as well as peace to avoid more conflicts and the rise of a new hegemon which could totally dominate most of Europe.