The decision is not inconsistent with the long string of cases that treats money as speech (which it isn't, but this case didn't create that rule), but in the process it has to overrule a 1977 decision by a non-reactionary Supreme Court super-legislature.  When I find a good analysis, I'll add a link.

ADDENDUM:  With Justice Kennedy having announced his retirement, it's clear the super-legislature will now veer even further to the right for the next twenty-five years; that means all the real action moves to the legislative branches, where it needs to be to really matter anyway.  Note that Justice Kennedy was, among other things, the key vote on all the gay rights cases over the last fifteen or so years.