First, Bootstrap did not standardize anything. It's a biased perspective to think so : most websites and most developpers don't even know about bootstrap. And those who know about it do not necessarily agree with it (per exemple I hate their JS coding style.)
Second, the myth about "changing your design without touching HTML". Sure, there're some cases where it's possible, but by experience it won't happen. Never. Sadly (or not), a redesign is always coupled with some HTML changes. Bootstrap does not change anything.
So, I think Bootstrap is far less important than, say, Wordpress was. It's a cool tool, useful for a "design dumb" like me to pull a quick demo without a true designer, but in the end it makes boring websites with boring code. It's also a overhyped tool, which won't survive (along with the whole stupid OOCSS thing.)