Because they improved downtown L.A. immensely:
In 1999, Los Angeles passed its Adaptive Reuse Ordinance, making it easier and cheaper for real estate developers to convert old offices to new housing. While the ordinance arguably jump-started the revitalization of downtown L.A., a key (though overlooked) element was pet-friendly policies in these newly converted lofts.
Walking dogs drove residents out of their homes and into the street at least twice each day. Elsewhere in Los Angeles, where single-family homes predominate, dog owners often have the luxury of sending Fido out to the yard to do his business. But downtown, dogs and their owners have become a crucial component of the rebounding neighborhood's culture.
Of course, if the office dog poops on the CEO's carpet, he'll still get fired.