Yes, quite ridiculous that each member has to make a comment to make sure they get notifications.
I can see the problem from both sides, both for and against. But one would think it could be managed from an administrative area, to either turn it on or off, or more logically, to allow the individual users to opt in and out of each planner task via settings when they don't want constant notifications, if for instance it is an item they physically check every day (not that many people actually check things every day, unless they only have one team, with one planner with one task (ah if life could be that simple eh?). Sort of defeats the whole idea of being a Team, if you are not automatically enrolled to receive notifications, but I do understand the need also to be able to opt out from time to time.
So if you have a large team, with say 400 members, I would choose to be the last to comment, as the first poor bugger to comment is going to cop 399 bland comments of people enrolling to receive comments without any actual important information being passed to anyone.
Awesome right?