I don't think anyone other than the designers knows how the game was designed - whether it is a convenient assumption for your argument or not. It would be safe to assume that they know (and use) the dice used by the majority of their players.
Again - there is a standard. Meeting that standard means playing the way that the vast majority of other players use.
Codex creep is part of the game. We choose to accept it and play with it. It has nothing to do with a discussion of dice.
Using dice that have a higher chance of yielding a higher result is the same as using loaded dice. Obviously, it has the exact same result - an advantage over the opponent based on the choose of the outcome generator.
What dice the use in Vegas is completely and totally irrelevant. Obviously. As those dice are standard for those games.
I have never played against anyone who choose to purchase dice that would give them an advantage over me - for obvious reasons.