I'm not sure I buy into the idea, but it couldn't have been sold any better. That security.txt generator is such a great way to get people on board. The whole website is really good at explaining the project.
More code || complexity == greater likelihood of bugs (including security bugs).
As ironic as a security bug in a security.txt serving module would be, it's probably best we avoid that possibility and let the ordinary, highly scrutinised file serving code handle it instead.
It would also be nice to have libraries for the popular frameworks