Why don't men wear pantyhose?

Men do wear them! More than you can imagine. Now many pantyhose manufacturers are making them for men and in most cases they are the exact same thing as women's repackaged (pantyhose will fit any body shape so there really is no need for his or hers).
The up side...
  1. Warmth when cold (though very slight).
  2. Prevents tick bites (important for outdoors people in Lime disease areas).
  3. If Graduated Compression type... (Typically non medical, denier 70)...
         They can prevent the formation of ugly varicose and spider veins!
         They can prevent leg cramps at night! (no useless medicine required).
         They really do provide you with more energy all day due to increased
          blood circulation.  (This IS a big deal I discovered)                            
          They can make your legs look better.        

   The down side...
     1. If worn under pants on a hot day you will be too warm
     2. Cost! (Compression type last much longer but even then 1-4 weeks).
     3. Susceptible to breakage: Cats, thorny plants, sharp objects.
     4. Some closed minded people think they are only for women and don't realize legs are legs no matter which sex they are attached to. (In 24 years never heard anything negative from people and I'm a guy).
In general guys will have no problem wearing the hose with shorts or under pants. People really don't care.  The benefits outweigh the thoughts of the minority. I have discovered I can't be without these:
Low rise.. fits under jeans, shorts, skirts. Don't let the packaging fool you...they work just as well for men.
Historically European men showed their stockings and it was a sign of wealth and status to have different colours and finer fabrics. Women historically covered theirs with skirts. One the biggest advances in machine knit stockings were invented by men for both men and women. Elizabeth I of England threatened death to anyone who shared the stocking knit machine technology with outsiders. Clearly hosiery has been traditional for Europeans for centuries, crossing through most major fashion changes right up until about the 1960s when Western culture threw the proverbial 'baby out with the bathwater'.

But back to the question: As men wore more trousers and breeches for all but formal wear stockings for men fell out of favour. By the time men were wearing shorts as an acceptable attire away from the pool or work only socks survived...which most agree look ridiculous with shorts haha.

Pantyhose came about when skirt lines got so short a stocking tops could be seen. They are a relatively new garment historically speaking and are easier to put on than stockings but not as hygienic (or classy and sexy hehe). As by this time men were not wearing stockings of any kind pantyhose are seen as an exclusively feminine garment.

Of course many sportsmen and outdoor chaps wear hosiery under the trousers for comfort and warmth. Soldiers wear them and lots of other very 'manly' men have been known to wear them. When I was a cyclist most of the men wore thick, soft tights under cycling gear in the winter to help with warmth and circulation. I'm six foot and very manly.

There's also a fetish aspect as well. I think some men wear pantyhose for those reasons too. Hardly surprising given how tactile they can be. Each to their own I guess.
source :- quora.com