Didn't I read somewhere that Crete was a minor distraction for the Nazis, but was enough to cause Hitler to delay the invasion of Russia for a few weeks? It seems those few weeks may have made a crucial difference.
It was the first major paratrooper deployment and the losses of the 8000 elite soldiers made hitler conclude that paratrooper drops were not practical (see also D-Day)
Like the article said, This is where the "Heros fight like Greeks" was established.
It also was not just Crete but the Itallian defeat and Hitler having to divert troops to rescue Musolini.
In fact they still have Oct 28 as a national holiday to celebrate the one word message the Greek Government sent the German General after a surrender demand, "No".