Why would a programming language want to use weak typing over strong typing?
At a very basic level, it'll also make it easier for beginners to pick up. (Probably one of PHP's reasons for success, irrespective of whether you appreciate PHP or not.)
That said, the general erosion of sound operational knowledge of memory management, pointers, etc. is a bit of a worrying trend, if only because you can't always stand on the shoulders of giants. (Someone still has to write microcode, high performance device drivers, etc.)