Add an option to the buffer geoprocess to select to exclude the source features from the buffer.
We can achieve this already with a few other steps (or a model if you are going to do it more than once in a specific way). Erase is currently an Advanced inclusion.
It will just be more efficient to have this included in a tool to run as one task.
Example scenario:
Create a 500m buffer around an environmental constraint.
Currently the buffer tool result includes the enviro constraint footprint which needs to be 'cut out' before further work is done using the buffer.
Edit: See Dan's answer.
