I believe that both your wordpress install and your plugins need to be as up-to-date as possible.
But when you handle a lot of wordpress installs it's not always feasible to update every plugin that has been installed on all those installs.
Also not every plugin update is that critical. Some are definitly, but others are not.
I would appreciate if some kind of level of urgency can be added to the plugin update notifications. So I can see if the update fixes a vulnerability or is just an update that adds a feature (I maybe don't need)