So is there a machine buried deep beneath Apple HQ that has a big read button labeled "make new product" and all they do is press it every now and then? Otherwise they do have to do R&D.
Do you want to talk about things Apple has innovated or things Apple has invented?
Proportional computer fonts, the modern mouse-based GUI, the PMP, smartphone, tablet, laptop. What haven't they innovated? Whatever they don't invent in-house, they buy up or license(FingerWorks, Anobit, AuthenTec, LiquidMetal, Corning Glass).