I think one thing that people need to take into consideration before criticising women who do feel offended (and yes, they do have that right and shouldn't be judged for it, imo) by men holding doors for them, is the fact that men (cismen in particular) do often take a very condescending approach to dealing with women. Very often its not viewed as condescending by the cisman because he's been socialised to believe that it's the "chivalrous" (or whatever modern incarnation you want to call it) thing to do. But it does come from a very condescending tradition. It's the same kind of guys who only seem to address women as "honey," "dear" and "baby" even if they barely know the woman, and really don't take what the woman says seriously at all. They're the kind of guys who go out of their way to practically force women into allowing them to carry things for them because "she might hurt herself" (or more likely his ego). All this because they believe that that's the way things are/the natural order. Having worked in really macho environments, I saw it on a regular basis, to the point where a woman or someone perceived as a woman isn't even asked if they need help...it's assumed.
I remember some days getting off work after having to deal with condescending cismen like that and yeah was pretty much ready to snap at any dude who so much as looked at me. And many women feel that way too. I feel like reacting negatively when women express that is more attacking women for their reaction to a sexist society and feeling frustrated with it than understanding why they feel that way. In that tradition women are always "b*tches" if they come off as angry or upset for a reason you don't understand, lesbians are of course "the worst man-haters of them all" etc. etc. etc. Typical misogynist stuff.
Is door holding in itself sexist? No. Like many other people in this thread have said, I've noticed that where I live it's pretty common courtesy. Whether you're a woman or a man you hold the door for the person behind you. It's not particularly gendered. But I think at the same time we need to recognise the way it can be and still is gendered in certain areas of society and the way its been used to belittle or condescend to women as less capable. Probably when a woman expresses discomfort or even anger about it, there's a lot more going on than just "omg this person opened a door for me." Most likely it's the last straw of her day where she's had men do things that legitimately are belittling and treating her as less capable.
