It's not laziness. It's being smart enough about their profit margins to not flunk How To Make Money 101.
Adding support for such low resolutions would cost more in development, maintenance & support time than the infinitesimally tiny increase in player base would bring in in subscriptions.
That's generously assuming the player base actually would increase instead of a net decrease (via the number of people who subscribe because it supports 640x480 being lower than the number of people who get turned off and decide not to try it after seeing it at such a low res).