I am more inclined to think that they ARE original. I did a quick clean-up of one that had those except in cast iron. I swapped in a cheap set of stainless grates and kept the cast iron ones!
I am sure it was because of the big gap between the Spirit II and the Genesis. I recently bought a Spirit E-330 to replace my 20 year old Genesis Silver B. The spirit is the same cooking area as my old grill and I did not need anything bigger. The new Spirits just did not seem any upgrade to my old Genesis while the cabinet style looked nicer if not functionally better. The sear station is a great addition and the side burner is occasionally handy. It was hundreds less than the comparable Genesis model. I am sure Weber was losing sales to comparable brands like Napoleon that offered that style.BTW, anyone know why weber brought back this style of Spirit grills? I noticed a lot of retailers are selling a new version of this Spirit instead of the Spirit II model. They aren't cheap anymore either. A basic 3 burner e315 retails for $699 Cad over here.