Edit: What's even worse is that we don't get examples of PHP code that was actually written with proper development procedures from the ground up. I mean, I was genuinely hooked by the headline..
I beg to differ. Disclaimer: I am an ex-drupal-developer, now-ruby-developer working at a startup for managed WordPress hosting.
Many people use WordPress because they know of nothing else. They don't find it good, exceptional or bad: they find nothing of it: it is all they know. They can't compare.
Again many people have severe issues with WordPress, ranging from security-holes, infected code, poorly maintained plugins to, most often, poorly implemented themes and horrible performance.
Then, some, really like it. But those are a minority. I've heard many WordPress-developer and -user utter the same words Dries (after Boris Mann) wrt Drupal has uttered: "This CMS sucks least".
You'll have to dig deep in order to find developers, users and other stakeholders, with the ability to compare it to many other alternatives, and who find it "exceptional". I've yet to meat one; eventhough all our customers are WordPress users.
If you're working with one of the larger WP-oriented managed hosts, we have the same clients and I have likely worked with your hosting.
So, well, here I am, nice to meet you :).
I agree... most people doing this kind of work don't have a lot of other options to choose from-- it is just what they know. They certainly neither know nor care to learn some other framework. Many of the people in this line of work are selling low or mid end projects to smallish businesses premised on leveraging functionality built by the large WP community.
That said, even though I could do projects in other systems:
I am usually working with agencies/consultancies who _want_ WP because,
it is super easy to find folks who can work with WP on some level,
their clients are familiar with WP,
and it is trivial to meet a bunch of marketing or CMS goals with it.
So while WP doesn't "suck the least" (I know of stuff I like better), it's still a good tool for a lot of reasons that have little to do with the code. For marketing objectives, you're going to have a hard time finding something objectively better for the total cost of ownership (there are, of course, better eCommerce, community forum, and application systems).
And your position self-selects for a particular kind of client... you're probably not seeing the folks who are doing the $10K-100K projects I see, in which the server management isn't farmed out to a hosting company.
Yes, it's not hard to make trivial stuff, but it's nearly impossible (and certainly a waste of time) to do complex things.
phpBB and Drupal have their problems, but they both improved their code-base alot, moving from legacy PHP software to software that is much more maintainable. The road to "high quality software" is long, but throwing software out of the window instead of slowly improving it is not the right solution either.
Both projects have high numbers of unit-tests and can guarantee backwards compatibility and regression free releases in a much better way than most of the software out there in any company, written in any language.