It's cute, and I guess sexy, but, Namor is a warrior and over 75 years old. I do not think he would want to look like an Instagram "star." Or the Bieber/Grande set. It has been said his strength, would make it not matter, having the long pants and armor ruin his under water drag coefficient. I don't agree though. A warrior would want every advantage in life or death situations. A warrior wouldn't give a little..... for fashion. Or he would not last for a second battle.
In the Throne Room, a regal attire maybe ....cape or fancy ceremonial armor would be OK. Keep the trunks for day to day please.
I'm pretty sure he has blue eyes too. In the Golden Age and Silver Age, it was often stressed with close ups and even words. Perhaps a nod to his mother's races' blue skin.