Mike Bernat has a new post to his blog today talking about what he considers the problem to be with both WordPress and Drupal - despite doing what they do well, they're not good examples for developers.
If a young developer said to you 'I want to learn by looking at existing code from a successful PHP project. Can you point me in the right direction?' Would you ever feel comfortable sitting them down in front of Drupal or WordPress code? What if they responded by saying: 'But they are the most well-known free, and open, products that use PHP. They're obviously doing something right, so why shouldn't I try to learn from their example?'
In his opinion, developers should set their sights elsewhere if they're looking for good examples. Both tools use what he calls the "old way architecture" that could hold developers back from some of the wonderful new enhancements that the language has to offer and best practices that might not be found in their codebase.
While some of the techniques used in WordPress/Drupal are undoubtedly solid and still state-of-the-art, the majority of the frameworks are ancient in web-development terms. PHP is growing as a language, and I for one want to see it regain some of the respect its lost.