You are plain wrong on all accounts:
Superposition is not a part of only the Copenhagen interpretation. You obviously didn't read the Wikipedia article you link to. It doesn't even contain the word superposition.
No, no one has ever observed superposed states, since the wavefunction collapses as soon as anyone try to observe it. It is not silly guesswork. The brightest minds in modern time have failed to come up with any other explanation. Einstein was only one of them. You can not say "the property has a given state but the state can instantly change when the particle interacts with another". Read about Bell's inequality[wikipedia.org]. It has been experimentally proven that you are wrong.
We, quantum physicists, don't have a clue why the nature is not probabilistic, but we certainly care to know why. I was on a seminar yesterday were the discussion came up again for the nth time. We are though very good at describing and predicting the phenomena. It is amusing how everyone that have read or heard some popular account of quantum physics thinks they happen to be smarter than the best scientists of the last century.
The same people who think they aren't fooled still enjoy the fruits of quantum mechanics. They use the power from nuclear power plants, they use semiconductors and lasers every day. Things that wouldn't be possible without quantum mechanics.
Quantum mechanics is very counter intuitive. Quantum mechanics is hard. It takes effort and time to understand even for the gifted. It is just sad how many people that haven't put in the effort or don't have the capacity to understand it feel free ridicule it. As Bob Dylan sang: Don't criticize what you can't understand