You're not wrong at all, but over the past decade or so(!) there may have been an air of 'why bother beefing this bit up more, it's all on the old core and we'll only have to re-do it again in six or seven years anyway."
Now that the new core is finally (?) here, that excuse can go in the bin and they can spend more time mucking around polishing stuff.
At its most dramatic, this analogy may explain why Bodypaint was left sitting on a park bench, gathering dust and slowly earning its own entry in Ripley's Believe It or Not.