Max Bohr explained the uncertainty principle in his Nobel laureate speech quite well (and in nontechnical terms) - even though it might be interpreted as some law today, it definitely began as a practical obstacle.
Also, the hidden variable theories seem to be about practicality; for all intents and purposes, because it would be practically impossible to know that such hidden variables exist, they are deemed as non-existent.
> Also, the hidden variable theories seem to be about practicality; for all intents and purposes, because it would be practically impossible to know that such hidden variables exist, they are deemed as non-existent.
Definitely not. Everyone would strongly prefer a model of the universe that was deterministic. Hidden variables don't get ignored just because we don't need them to make predictions. We really really really want them, for their own sake, but we cannot make them work.
I think you are folding two things together that are related but not the same. Hidden variables are about the state of an entangled system. The uncertainty principle can be applied to measurements taken of an entangled system but can also just refer to two quantities of a single particle such as it's position and momentum.
Also, the hidden variable theories seem to be about practicality; for all intents and purposes, because it would be practically impossible to know that such hidden variables exist, they are deemed as non-existent.