I wonder how much of this has been driven by ZIRP, making companies a little bit more lax on what they were spending energy on. Teams are large and devs are decoupled from the end user and end result (PMs, designers, leads, managers have more say on the product being created). That, coupled with devs traditionally, IMO, being enamored by system design and wanting to create even more efficient systems for building things, and given that is the one thing they have direct control over (not the end user experience and product), they would naturally want to focus their efforts on improving their systems for building things, at the sake of missing out on the bigger picture, which is that rebuilding systems has a cost that does not directly translate into net user benefit.

When you're closer to improving the bottom line in terms of sales and user joy, I think there's a greater likelihood that you focus less on spending time rebuilding your platform to whatever is currently hot on the scene. (Not to mention internal promotions may be skewed towards clear engineering efforts vs. more qualitative user-perceived improvements.)