Suits generally are pretty comfortable though, other than the shirt and tie which give me something close to claustrophobia. Some of my favorite pants for lounging around the house are suit pants.
Business suits are limited by the choice of fabric and the specific cut. To make them more comfortable they would have to compromise the design, and the fabric would need to change.
Comfortable clothes usually follow the movement of the body with little to no resistance, either by stretching with the skin (tights, never wore them but I hear they're comfortable) or baggy clothes, usually with synthetic fibers.
You can find casual suits that are basically track suits with a business suit general look but I wouldn't conflate them.