Personally I believe that software design is a highly subjective art. People that are meant to maintain a piece of code are different. Some may be more creative and less pragmatic, others may be more structured and clean in their design.

The truth is that there's no silver bullet. You can build software based on hierarchy of classes because your mind works better with that structure, but others may find it completely inappropriate. We're human and our mind works differently from one another.

In that sense I truly believe software is much closer to art than engineering.