"PHP was not designed by good language designers. I don't even think it was designed by people interested in language design."
PHP wasn't designed, period. It was a bunch of ad-hoc functions and features that weren't expected to gain such a widespread acceptance (it originally stood for "Personal Home Pages", not "Enterprise Web Sites" -- lest we forget). At the time, Perl/CGI sucked and nothing else was free.
By the time people started approaching it from a language-design angle, it was too late -- there was the hobgoblin of backwards-compatibility. Just look at the inelegance and overlap of strpos(), stripos(), strrpos(), strstr(), stristr(), substr(), etc.
Exactly. I talked with the designer of PHP, Rasmus Lerdorf, sometime around 2001 or 2002 at one of our LUG meetings. Very bright guy, and impressed upon us that PHP was truly an organically grown language. It started as a Perl app, later rewritten to C. Rather than butcher the history, I'll point you off to http://us2.php.net/history.