You really have to own a 4k TV to get any use out of either the PS4Pro or the Xbox One X, anyone without a 4k TV will be happy with the initial boxes. They're really aiming at a subset of gamers and I don't really understand, in particular, Microsoft's motivation here, since they're not out to sell TVs.
Not entirely true ... Some Enhanced games offer Performance mode at 1080p 60Hz and all the X360 BC games are significantly smoother too. At the very least the same old games load substantially faster.