So my idea is not so much that S.P.E.C.I.A.L. needs to be changed, but the effects of each one should affect every aspect of the game. As an example, while Strength should change how much you can carry, and your ability to swat things with blunt obhjects, it should also change other statistics as well. For instance, as someone who has strength out the ass, you might tend to look more fearsome and intimidating, making your speech challenges more difficult. It might also change the way you move around, for instance, greater muscle mass mean more to move, therefor you might move slower with more muscles.

The biggest difficulties with this would be 1) implimenting these changes, requiring a mroe adaptable system, where you and the world around you change with your stats. 2) Eplaining this to the player. there's a dozen and a half skills that these would have an effect on, and there are seven skills that could alter all of those with every change. (this might be fixed with a more interactive set up process that simply showed what each S.P.E.C.I.A.L. would change)

So is this something that is pheasable, that being, can it be done and would players be able to understand what was going on with each change, and if it was, would you want to see it in a Fallout game (future, DLC, MOD)?

SPECIAL already has it's bonus and consequence, above 5 is bonus and below 5 is consequence, I don't like the idea to be forced on consequences just cause I raise another stat.
So a big no from me, even if what you say make sense realistically, it's one of those "realism" things I hate being brought into the game.

No, because you end up with having to keep putting more and more points in to stay where you are - If you put more into strength, you're then going to have to put more into charisma, which is going to weaken something else... Its also not mutually exclusive for someone who looks tough to be inviting and charismatic.

That said, I think there are systems that do use the sliding scale between two attributes, and they work well, but not in fallout. It would need more than just an overhaul, but a complete attribute system redesign that would stop it being SPECIAL.

I'd say get SPECIAL up to the originals standard before thinking of fluff improvements/changes.