Just goes to show how both Canon + Nikon have become volume sellers, with the emphasis now on shifting product to new customers (especially new emerging markets), rather than focusing on better new products for existing customers.
I am not sure if I agree with this statement. Two top lenses: Nikon's 14-24 f/2.8 and Canon's 70-200 f/2.8L IS Mk2 are clearly new better products for existing customers.
Nikon and Canon are able to sell large volumes of lenses because of their excellent DSLR bodies, extensive lens collections as well as massive support from 3rd party lens sellers (Sigma and Tamron). Sony and the m43 consortium still have a long way to go in terms of lens selection.
They are...but they also cost in the neighborhood of $2K+. Not exactly an easy sell for many if not most existing owners. Will I buy the 70-200L IS m2? You betcha! When? After I can manage to save up for it.
Both Canon & Nikon are among the best companies in the world that put in a great deal of emphasis on R&D (i.e. "focusing on better new products for existing customers") ... if they did not, they wouldn't be where they are today ... when Canon & Nikon make new products they incorporate suggestions & recommendations of their customers (many of them are Professional Photographers). The success (of serveral decades) of these two companies is not an accident. The best products in this world always cost much more than run of of the mill stuff and that is the fact of life.
5D MK III, 16-35/2.8 L II, 24-70/2.8 VC, 24-105/4 L IS, 70-200/2.8 L IS II, 100/2.8 L IS, 40/2.8, 50/1.4, 85/1.8, 150-500 OS, 600EX-RTx2, ST-E3-RT, Rokinon 24/3.5 T-S, D7100+18-300 VR, YN568EX, 055CXPRO4+468MGRC2, 190CXPRO4+322RC2, Gorillapod Focus+496RC2, CamRanger, B+W filters, Konova K3/31.5 etc