I guess like J Daddy alluded to, it comes down to the electronics. I purchase older modern locomotives myself due to the prices, but how much longer will 10 year or older locomotives still function? I have bought some Atlas locomotives that were a little beyond 10 years, but I wanted them for my collection.
Prices are down because of the market for new offerings, but it may also be due to the uncertainty of electronics and parts replacement. If I have to pay $200-$300 to upgrade a locomotive, I will definitely find the least expensive used ones to make it worthwhile.