There is a fine line between being critical and being fussy. As a designer, a pair of critical eyes helps to differentiate the work’s quality. It is not only for judging others’ work but the most important work to be judged is our own. Sometimes we might leniently allow ourselves to accept our own work which are just barely nice enough. Similar to the school examination system, it is the final 10% that makes a piece of work achieve a recognition of excellence.
Developing a critical eye can unfortunately also be seen as being fussy or having an expensive / high maintenance taste.