I am going to add an option to the Project Properties dialog so that you can select "None" for the Compiler Configuration. This way, you will not get a compiler tag file. This will be an improvement over creating an empty one yourself.
As for being able to choose which tag files to use on a per-project basis, well, there are so many ways to go about this already, I think this is just a matter of people understanding better how to use the project system. You can add Auto-updated tag files to your workspace, which are only active when your workspace is active. You can also add sub-projects to your workspace (and even specify that they be tagged separately).
With respect to tagging, the Compiler Tag file is the only thing that is Project/Configuration specific. Your workspace is the world you are working in right now, a project is just a part of that, so the tagging system needs to be able to see outside of your project within the current workspace. It would make the whole system intensely tedious if you had to switch projects to find a symbol outside of the current project. If you want a more restricted world view, you should be using a more restricted workspace.
Language specific tag files are really intended to be global tag files that you expect to use always with that Language. There is an outstanding feature request to add check-boxes to this dialog per-tag file so that you can easily disable a tag file -- I also plan on implementing that in a future release.