The accessibility and user-friendliness of GMRS is a big plus. Also the fact that the $35 / 10 year license is a family license is also an advantage.

It should be noted that most of the leadership for our local GMRS activity comes from hams, with the technical knowledge, the long history and know-how of emergency communication methods, and the decades-long experience working and establishing relationships with local fire departments, hospitals, etc. When the local ARES group provided communication support for the Oakland Fire 30 years ago that wiped out 3000 houses, they faced the "Who the hell are you?" problem when trying to get places. That doesn't happen now. The Fire Chief knows who we are.

The GMRS nets here are based almost entirely on ham radio protocols. I think the sense of formality may also be inherited from that.

To my mind there's a clear progression from FRS to GMRS to Amateur Radio. FRS (Family Radio Service) no license required, get a pair of radios at Home Depot, and you're in business, although with the least power and capability. GMRS, inexpensive license, no test, and you can use repeaters, which is a big expansion in coverage. Ham, you have to study a bit, and it has the most technical and communication options. (Note that Amateur frequencies don't overlap with FRS/GMRS; you need both licenses to use both.)

For most people interested in emergency communication, GMRS is the arguably the sweet spot. But there are advantages in also having a core of people with a deeper understanding of radio. I'm happy when someone gets a GMRS radio, and I'm also happy when someone wants to go deeper and look into amateur radio.