I understand that modern outer layers are more functional. A leather jacket, for example, can be dressed up or down so as to be worn in a variety of situations. It is also better at keeping you warm.
However, I think capes/cloaks are more aesthetically pleasing garments. It also feels good to have the fabric flowing around you as you walk. But what do you think?
Because we don’t ride horses anymore.
This is the real answer. For many more questions too. One day in the distant future people will ask why don’t we ---- anymore and the answer will be because we don’t drive cars anymore.