I was listening to some older folks while at lunch hour and they were discussing How nice it was to have a first lady with some class for a change. Trivial searches will find lots of crazy theories about Michelle Obama, and for her time as First Lady (of the US or Arkansas) Hillary Clinton had a pile of conspiracies around her. Melania Trump in turn has lots of negative (though not necessarily mainstream) press attention surrounding some of her actions and motivations. Donald Trump also took potshots at Heidi Cruz, the wife of his main competitor in the Republican primary.
That said, I don't really remember Laura Bush being assaulted in this manner, and all I can find (now) about Nancy Reagan and Barbara Bush is relatively positive. Is this tendency to target the First Lady or even wives in politics a particularly new development?