I was having this conversation yesterday in the gondola at Stratton with my skier buddy who is a self proclaimed snowboard hater obviously him and I are very good friends and go ride the mountain together so his argument for his disliking of snowboarders is that as previously stated we all always seem out of control on the mountain. Also because there are many of us that will push ourselves on terrain we can't really handle yet we have a tendency to just slide down the mountain on our heel edge thus ruining the terrain for the people who can handle it. My response to him was basically that I think the problem lies in the fact that there are just way more "new" snowboarders than there are skiers so there much less overall experience riding the mountain on a snowboard. Also new snowboarders do tend to take up more space on the slope than do skiers due to most making very wide turns as we learn to link and get more comfortable turning in a smaller radius. Skiers overall mountain footprint is smaller as the turning principles are just different from snowboarders.
He did agree with what I was saying and I think that lightened his perception more. In terms of the attitude, there are plenty of shitty people that both ski and snowboard so it really just comes down to the person