The best thing about Bootstrap is that it's ubiquitous -- every frontender has heard of it and can easily jump on a project that uses it -- and that there are a lot of integrations with frameworks, like angular-bootstrap or react-bootstrap, that don't tie you to using the stock jQuery plugins.
This framework doesn't have anything that relies on JS magic, like button dropdowns, collapsing panes, etc, which are useful in real-world apps. I certainly wouldn't want to reimplement my own versions for every project.
Bootstrap's cruft is a non-issue if you use the customizer [0], or, better yet, selectively import the components using LESS or SCSS [1].
The JS components are a non-issue, I agree. However, the one problem with customising Bootstrap is if you're using a front-end dependency manager like Bower, as far as I am aware, you cannot easily customise the dependencies in Bootstrap if using Bower or Component. Sure, I could use a custom generated and downloaded version of the compiled CSS files, but then I loose the ability to change colours, fonts and whatnot using variables or the internal helper functions...
This framework doesn't have anything that relies on JS magic, like button dropdowns, collapsing panes, etc, which are useful in real-world apps. I certainly wouldn't want to reimplement my own versions for every project.
Bootstrap's cruft is a non-issue if you use the customizer [0], or, better yet, selectively import the components using LESS or SCSS [1].
[0] http://getbootstrap.com/customize/
[1] https://github.com/twbs/bootstrap/blob/master/less/bootstrap...