Undershirts do have a place in style or fashion, which is why the vneck and white t craze started. Just because you or others still use them doesnt automatically make them "in" style, especially when you're wearing it out of necessity, not for show. The idea that they're not in style mainly applies when you're dressing to impress, not to work. Its not aimed at guys who wear ties and business suits, as it makes the undershirt nearly invisible, so it's pointless to argue whether it's fashionable or not. If you need it, then by all means wear it. Personally though, wearing undershirts just makes me hotter and makes me sweat even more. I'd rather skip it, sweat less, and use a deo that doesnt stain dress shirts.
I think Kohls has Ralph Lauren Chaps line that, IIRC, are thicker than average, but not as thick as the RL regular line?
I never said me or others wearing them makes them "in style", I said that I don't care. I wear them for the purpose that they were made - to protect my shirts and to avoid visible sweat on my outerwear. This is true for work, going out, wearing a suit (I don't at work), etc. I find that in a city like Houston it is pretty essential year round and I am not even that big of a sweater. I understand that some people might see a difference in dressing to impress and trying to be pimp in their shirts but I still find it amusing to say something like "wearing undershirts under your shirt is out of style.