Yes, TFTD was kind of lazy in that regard.
But I'm asking for the means for modders to do something more with it, from making TFTD underwater missions actually feel like it is underwater (no throwing very far, for example), to making new environments for battlescape, like Space (where everybody can fly regardless of armor, if you ignore realism for the sake of gameplay), High-Gravity (something like -10 to -20 penalty to Stamina and Strength), Low Gravity (+10 to +20 bonus to Stamina and Strength), Extreme High Altitude (Constant Stun damage if you aren't wearing sealed armor), Corrosive Air (Constant to Damage to Armor) and so on.