As a side note, I believe what was important about mod_php was safe_mode. It is a rudimentary file i/o sandbox that only allows you to open files with the same UID your script was created with. That enabled shared script hosting, you don't have to use one process per user which was important for the nascent "web hotel" businesses.
Performance was worse than Perl (which was the dominant language at the time, and had decent template frameworks too), security was worse, the language itself was a stripped down Perl 4, but deployment was so easy you just had to install it and you had yourself a shared web hosting environment.
I see now that safe_mode is removed from PHP 5.4 so perhaps we're full circle now. I wonder what shared hosts are supposed to replace it with?