I mean come on, swimming a skill, really?
How many people in the world can't swim? (enough to make it plausible that some characters can't swim?)
Edit: I understand that you (probably) mean that gameplay-wise a PC that can't swim is crippled by that and should never happen ~its detrimental to gameplay... But gameplay can incorporate disadvantages. :shrug:... The game could have a background trait where your PC grew up in a desert caravan, and spent his life traveling a circular merchant route between settlements, spent his days setting up tents, hauling boxes and pounding tent stakes... And it could mean that he's a good deal stronger than usual, but has never seen water deeper than his chest. :shrug:
**Something else... good characters often have character flaws.
People need to see it for what it really is, they are trying to whittle down the skills to their basic parts, to the skills where they all belong in and then the can add in new skills once the skill system we have is perfected. Having more skills for the sake of having more skills does not give you more meaningful choices or make the gameplay better. If you just start cramming skills into the game, chances are really good that you will get skills no one ever picks or skills were people sink their levels into and then you find out later in the game that they are struggling or can't get anywhere because they aren't strong enough to move forward in the game, which happened often in Daggerfall to some people.
The point of an RPG is not one of assured success, when it becomes so, I'll give them up. Still... a well designed RPG will at least try to anticipate the less obvious/popular paths to success. In Fallout the bruiser PC/player can barge in and kill the main villain ~maybe; but there are ways to talk your way into an audience, and even attempt to talk him out of his mad plan... Previous play-style weights the odds that he will believe, or be convinced.