My guess it that it’s reflecting what you get in the http webhooks, so they probably wouldn’t remove the attributes silently as it would break many apps.
Additionally they’ve been working on the new event system so I don’t see the webhooks getting new releases until they’ll probably eventually deprecate it.
Events are still in developer preview About Events and webhooks
I’d recommend checking it and if you have any feedback about it open a discussion dedicated to it or ask in the general thread: Next Generation Events now available in Developer Preview
You’ll get more chances to get a answer and possibly an update going into your direction as it’s where Shopify is putting the efforts right now.