Whilst the "Disable All Tools that Write Output" option within the Runtime Settings in Designer is useful.
I think a Workflow "Live" status / indicator could be really useful?
One key thing we have to seriously remind people whenever they start using Designer, especially when they are potentially picking up a workflow that some else has built is to sternly remind them that they need to understand the workflow outputs properly before pushing the run button!
One thing we do to get this message across is to demo the disable outputs option.
What would be better is to have some kind of interface / visual similar to the browse tool visuals that are created. But within the canvas / workflow / runtime config window?
This would instantly draw users attention to the fact that the workflow is connected to live outputs and that they should proceed with caution / turn off outputs etc.