What I've wanted for a long time about this game is that you can build muscle mass for more damage in combat. Couldn't this be incorporated somehow?
otherwise it's one of the few masterpieces here
Attack includes both strength and also expertise in fighting. Damage is done by comparing net Attack to net Defense, not just subtracting Defense. Your Attack can be lower than their Defense and you still do some damage on a hit, and if your Attack is much higher than their Defense you can do a lot of damage even with a dagger.
Strength does go up as you gain levels, but not ridiculously fast like some games. The Attack bonus from Giant Strength potion reflects higher strength, but it doesn't help much if you don't have the skill to land a blow with that increased strength, which it's why it's a percentage increase instead of a straight number add.
In theory you can do the giants quest Pickuyuprock without needing a Giant Strength potion if your level is high enough, but most players complete it well before their level is high enough for that.