Yes, you can use just the CSS, but all the scripts are tied to jquery ,since they are jquery plugins.

Regarding bootstrap , i'm a designer, and i dont mind people using it. The heck i used it myself.

It doesnt turn server guys them into ergonomists nor usuability specialists , but they know that their code will render well on all the browsers with virtually no test. I prefer people using bootstrap sites to coders that try to come up with their own design and just cant...

Now i design webapps and sites that need to stand out more than the basic bootstrap look but bootstrap can be a tool to work upon too.

Of course there will be a bootstrap backlash like there is a jquery backlash from javascript "purists". But these purists tend to forget what was web development before jquery or before boostrap ...