Actually, fun fact- pocketless may be less practical, but they work on a space vessel, something that has a lot of moving parts that require maintenance and must operate to very high standards.
IRL people that work in and around those conditions are generally not allowed pockets to prevent any kind of pocket junk falling into a machine and potentially jamming it, so this isn't a practicality thing, it's a SAFETY thing.
Ignore the fact that the Enterprise routinely takes immense amounts of punishment
The lack of pockets might keep junk from falling into machinery, but it sure as hell doesn't keep junk from falling out every time the Enterprise takes damage.