PHP wasn't always what it is now, that's OPs point. They are where they chose to go. Probably in the search of legitimacy, they chose to follow the most enterprisey language.
Why NOT Java?
Since I don't have to use PHP I'm not too upset. I was really just lamenting the state of the world.
PHP is heavily based on C so choosing to make it's OOP features like C++ isn't a big leap.
Plus PHP is still far less enterprisey than Java so maybe the OO model isn't the real issue.
/s
Zend has made a lot of good decisions (and a few painful but livable bad ones) over the last decade.