This was something I didn't realise until Demonac held both next to each other at the Toyfair and pointed out all the panels that were different... a lot more than I was expecting, but maybe a waste of expense if the difference isn't easily noticed like Cyclonus, First Aid or Streetwise.
They could have done a redeco of Optimus and invested that remoulding into another toy that could use it, like Wildrider from Dead End or Breakdown.