Provide a method to use compiled Bootstrap files from local directory

It is very easy to do this, you just modify your .info file to point to the ./bootstrap/css/bootstrap.css file inside your theme.

No. That is not how this project works. If you decide to do something this manual, you are already going against the recommendations of this project so you will undoubtedly encounter issues like this. We cannot, nor will we provide every use case possible. This will only confuse people in the documentation (ie: too many options to choose from). It is simply better to give the supported (and widely used/verified) methods of implementation.

Again, Bootstrap Library is not supported nor is it a recommended method of injecting theme level functionality. If you use this module, it is at your own risk. We will not provide support for something that isn't really necessary.

Not really........................

If you're not manually compiling your own source (to customize) and you're simply loading the default compiled framework, why do you need to serve it locally from your server?? A CDN loads faster for everyone involved (your entire world wide audience).

But you just said you weren't compiling....... I'm so confused.

Add officially supported way to use compiled Bootstrap in sub-theme.

compiled === already compiled/not source, no more compiling is necessary

You are the only one that I know of that is doing it this way.

Understanding how to compile LESS, SASS or any other preprocessor includes being able to debug when things go wrong.

I explained this in #2236923-4: Errors while compilin provided LESS files.

If you are getting errors that a "variable doesn't exist" then your variables.less file is likely doesn't match the code that is trying to compile.

I've made a video (sorry, no audio... my computer/app is acting up) showing a fresh download of 7.x-3.0:
http://monosnap.com/file/YYt5O5ysPd254hPGYyfwe7dNCPfC2Z

The error you're encountering is: variable @container-lg-desktop is undefined.

If you had searched for the error you were receiving in our issue queue, you would have found #2166063: Variable @container-lg-desktop is undefined. You could have easily come up with a solution (like I did in the video).

It's unfortunate that even stable release sometimes have bugs like this, but when dealing with an external framework like Bootstrap, it happens. The fact is though, we have already fixed this.

I don't really think anything of you, except maybe that you're still new to drupal.org issue queues. The reason I say this (despite your 6 years on d.o) is that your attitude of expecting support help for some basic LESS/compilation questions and and constant creation of question issues are proof of that. There is an established protocol and workflow for creating issues, none of which you followed (especially after I said to search for your question):
https://drupal.org/dcoc
https://drupal.org/node/317
https://drupal.org/node/314182
https://drupal.org/node/73178
https://drupal.org/node/73179

I have relented to reproducing and fixing your "error", but this has now taken time out of my day to hand hold you through some pretty basic LESS/framework concepts. I have closed #2237749: Abuse of Issue Queue, but please... seriously, stop spamming this queue with things you could easily search for in both this queue and on the internet abroad.

In retrospect, if you had simply posted the compilation error in the first place, I probably would have closed it as a duplicate of #2166063: Variable @container-lg-desktop is undefined and gotten you on the right track.

So in my error, I didn't ask for the compilation error you were having and I must apologize. I deal with many issues created almost daily and issue questions like "Why isn't this working" are almost immediately dismissed.