I agree with MSW that the women's march coordinators made a tactical error in not allowing pro-life groups to march under a banner. Having a "big tent" approach is nearly always the way to go. But a lack of inclusion at marches and parades is nothing new. It was not until very recently that the Ancient Order of Hibernians prevented gay Irish groups from marching in the St. Patrick's Day parade in NYC. For many years, the parade's Grand Marshal, The Cardinal Archbishop of New York, was just fine with that decision. So exclusion from parades happens on both the left and the right.

As for the women's march in Washington over the weekend, I like what my favorite commenter at the New York Times, gemli of Boston, had to say about it: 

"This march was not about offering coherent political alternatives, or providing a structured response to the challenge of an illegitimate administration. It was more like a gag reflex to a noxious stimulus. It was our democracy’s way of throwing up."