JQuery is single file too and that's a big part of it's attraction. Simplicity is a huge plus, not only for users, but also for the developer who is forced to be disciplined.
I haven't used bottle yet (just starting), but I'm very impressed with the templating code which seems very powerful and simple. Including the templating system along with the rest of the framework in a single file, forced the developer to think about it more.
But part of the advantage with jQuery being single-file there is ease of deployment. Python isn't quite as handicapped in this areas as Javascript is. A single line in requirements.txt can add something as complex a complex library to your project without a second thought.
And you'll end up with the complexity of dependencies with mismatched and/or incompatible versions. Adding a dependency explicitly to the source code is the ultimate, albeit somewhat inefficient, solution which is often useful. In Python, for example, BeautifulSoup has long recommended this practice.
I haven't used bottle yet (just starting), but I'm very impressed with the templating code which seems very powerful and simple. Including the templating system along with the rest of the framework in a single file, forced the developer to think about it more.