It would be great to have this more readily available. It would be very useful for developing/testing flows.
Right click would include a context menu for disabling or enabling an individual, selection, or group of nodes.
It's already quick and easy to enable/disable nodes by using the filter in actions...
...or using ctrl-8 as a shortcut.

Hi @poldim
I've been making a number of improvements to the right-click context menu for 3.1 - primarily around actions on the flows themselves: Improve UX around hiding flows via context menu by knolleary · Pull Request #3930 · node-red/node-red · GitHub
I have work in progress to add more context-menu options for groups.
Adding enable/disable options for nodes would fit in with this work.
So stay tuned for 3.1.
Nick