Well, as a younger guy, I don't know how it was 10-15 years ago. All I can say is, I think most guys over 18 (or, say, 20 ?) are quite comfortable with it. In my opinion, you get more comfortable once you're out of your teen years. Psychologically, you care less about what others will think or say. And physically, your body is also more "mature".
As far as I'm concerned, I only started showering regularly in open showers around 20. Before that, I wasn't scared to show my body, but I would only have showered in public if that was an absolute necessity. I have mates who had a real problem with nudity when they were younger, and who know have not the slightest problem anymore. I have other mates who never had any problem and seemed to get naked whenever they had an opportunity. So I think it really depends from one guy to another. I don't think there's really a trend towards being more or less comfortable than before.