In thinking on this some more, I see some critical differences between FRS and most other radio services. Unlike amateur or even some GMRS, it's not a hobby in and of itself. People use the FRS radios to support other hobbies or activities of all kinds, but they don't engage much in the usual radio hobby talk.
GMRS is a whole different animal in some respects, but in part, it's an extension of FRS. The licensing is now primarily family based. Some users try to turn it into a Part 90 clone and others treat it as a hobby much the same as the amateur service.
In business, it's used primarily for short range in-house communications of all types. Hospitals, offices, hotels, paving operations, and a lot more all use FRS. But it's a tool and gets treated as such.
Given the vast number of FRS radios sold in the last 20 years, it certainly has its place. From a scanner enthusiast points of view, it may seem to be mostly unused, but given the very short range of the units, there could be lots of activity just a few miles away and it would likely not be heard.
Like a lot of users, my FRS stuff only comes out a couple of times a year. But I think it's alive and well running mostly under the radar.