How would you like it if you had one of those luxury performance cars where the manufacturer offered 3 or 4 variants of chassis, top plates, towers, you name it, so you needed to buy the lot to be competitive everywhere.
I don't think AE have ever done that. The TC3 went on for 5 years with little change, and is still competitive. With the TC4 they are offering a flat chassis and a tub chassis. We should be thankful.