Code review takes too much time. You can take a painting that took 100 hours to make, and start delivering useful criticism after a minute or so. Giving useful feedback on a programming project that took 100 hours will take much, much longer.
Also, art is meant to be examined - that is its primary purpose. Source code, not so much.
Also, art is meant to be examined - that is its primary purpose. Source code, not so much.