~~Lots of~~ Some* wireless access points support operating in either a client or bridged mode. Client mode usually implies (not always) it NAT'ing the WiFi connection similar to what a home router might do with your internet connection. Sometimes client mode is synonymous to bridging which is what this Pi is doing.
So yes, there's been a market for this on lots of consumer devices for quite some time. Most people just don't know it exists.
Edited my comment a bit as doing a bit more research its not quite as common as I believed but does exist on a number of consumer devices. I still stand by my point that most people don't know about this feature of their hardware when present as most people don't understand the difference between a router and an access point.
I guess the main issue is that Ethernet ports are going the way of the dodo.