Rasmus has clearly stated that PHP's ugliness is a feature.
http://osdir.com/ml/php.devel/2002-10/msg00704.htmlHe freely admits that he is a crappy programmer who can't write languages. His goal was to re-use code because he hated (hates) programming.
That doesn't really explain why contributors perpetuate the atrocity, but understand that PHP is the way it is based on a set of priorities that many of us do not value.