Yes they should have created more but again Italy too didn't create much against England does not mean Italy also useless. Infact germany created more chances against England than Italy.
Football is a funny game, where the score is usually close and where one moment can change everything, especially in a knockout format. If Müller scores his chance, there is a good chance that the momentum favors the Germans to win who then have a manageable path to the final. There would be a good chance that Löw ends his tenure as a respectable finalist or maybe even champion. It would be a complete different narrative.