Your post has helped me so much. I'm a pretty slow learner so don't go along with the idea of learning serveral languages - especially when one of them - PHP - is a bastardised, inferior version of something I spent years learning - Perl. So many programmers use throw away comparisons betwen PHP and Perl as if their syntax is virtually the same but I've had terrible trouble having to use PHP for some web projects coming from a Perl background. PHP syntax makes me wince, compared with the elegance of Perl. Unlike you multi-linguistic programmers I HAVE to specialise in 1 server-side scripting language to get anywhere with it. I believe in sharpening a single tool rather than trying to be a master of all trades. Perl, with CPAN, is enough to occupy a lifetime anyway so I don't understand where all you multi-linguists find the time to be excellent in so many languages. Competent, maybe, but excellent, no.
I've reached the point where I'm considering leaving all PHP work well alone because it's having a detrimental effect on my Perl skills. It just encourages so many bad habits.