We don't necessarily want to constrain future tyranny in that way. Voluntarily giving up certain degrees of freedom is the best way to solve tragedy of the commons type problems; we don't want to prevent future "tyrants" from enforcing pollution controls.
I can't wait for people to do things with blockchain but it's probably the most hyped technology for the least actual real-world use. The bitcoin paper was all the way back in 2008 so I'm curious when (or if) I'll see the first blockchain technology that will actually catch on outside of small niches.
Block lchain is a great tool but the really important thing is to have the public ratify decision making.