The weather isn't worse in the winter in NY than in Copenhagen. You can wear a full dress coat (coat/skirt guard) and hat like they do there. In the summer it is hotter (not generally 95 (high average is only 84 in hottest month), but it does get up there), but the point is in general if you can walk in the weather, you can ride in it. I live in a city hotter than NY with some hills, but its true I can wear shorts and sandals in the summer usually. But for the vast majority of the time, I could wear most any clothes for my 6 mile commute each way. If biking ever gets mass appeal for normal transport like it has in some places, it will be because most people are just hopping on and going, not through sport biking with separate gear, so the article has some points I suppose even if it must be from more of a style angle and we all know Dutch bikes are all about utility (although the author does not ignore that).

Amsterdamize collects some of the heated responses to the article and comments on them:
http://amsterdamize.com/2009/04/16/new-amsterdam-times/

IBikeNYC chimes in as well:
http://ibikenyc.com/