Managing or working with any team of highly motivated, passionate and creative developers presents this problem, as a group: how can you objectively judge code while preserving the sense of ownership by the author?
The first step to objectively judging code in my opinion, is to separate it from the individual who wrote it when discussing the code. For a lot of people this is easier said than done, particularly for younger engineers like myself. Younger engineers tend to have "more to prove" and are thereby far more emotionally invested in the code that they write, while older engineers whether by experience or simply by having written more code than their younger counterparts are able to distance themselves emotionally more easily from the code that they write. Not to say older engineers aren't emotionally invested in their work, in my experience they typically are, it's just a matter being better at picking battles.