Because the whole problem it is solving is that both matrix multiplication and elementwise multiplication are frequently used enough that there is API fragmentation in popular matrix-using Python libraries between places where * is used for matrix multiplication and places where it is used for elementwise multiplication. Read the linked PEP, this is addressed, at length.
As in how ruby does it: http://www.ruby-doc.org/stdlib-2.0/libdoc/matrix/rdoc/Matrix...