It's only in hindsight that you can say the hope was "vain"; many Eastern European countries are doing fairly well, as are most Balkan (former Yugoslavia) countries. Further back you can also look at post-Franco Spain as a success, or Germany after the second world war.

At some point you got to say "okay, we'll try again with you guys". Sometimes it works out, sometimes it doesn't. There's a fine line to walk here, but in the end it's the only option there is other than perpetual hostilities.