You are being optimistic due to the fact that you are cherry-picking items from the Quran which support a tolerant interpretation of Islam, and you are denying the fact of reality that most Islamic nations practice some version of Sharia law, which is not tolerant at all. Just because there are some Muslims in your school cafeteria who mingle with non-Muslims does not mean that Islam is a tolerant religion. Projecting your own liberal psychology onto the many Muslims of the world is not realistic, it is wildly optimistic.
Remember: I have not read the entire Qur'an, and I do not know much about Sharia Law, such as whether or not it is supported in the Qur'an. My studies have not reached that, yet.
It seems to me that you are completely ignoring the fact that many Muslims are tolerant, and tolerance is supported by the Qur'an. Instead, you seem to be focusing on the bad, and that the bad somehow cancels out the good.
My conclusion: a religion cannot be intolerant or tolerant: that falls only to the people who follow it. There are tolerant Muslims, AND intolerant Muslims. I admit: the intolerant ones do appear to outnumber the tolerant ones. Islam itself is just a form of worship.
I don't judge a religion by the counties that use it as a political system.
EDIT: If tolerant Muslims do exist, that itself is, in my opinion, enough to show me that tolerance is fully compatible with Islam.