Chris, I totally agree with you. Originally the word "3G(3.5G, 3.75G, 3.9G then LTE)" meant to stick with existing frequency and infrastructure, meanwhile 4G meant to build brand new infrastructure (such as WiMax or XGP). The word "4G" is not just meant "faster data service".
I also think the word "5G WiFi" is confusing between "5GHz WiFi".
Ugh...seriously? "5G" as a name for next-gen wifi? Why??? Didn't the confusion with cellular tech ever occur to anybody? Maybe the next Kindle will support both "4G" (cell) AND "5G" (wifi)? I guess I can understand the concern over "n" to "ac" etc., but using the next "version number" from a totally different technology doesn't help.
Just my opinion...
I received a Kindle Fire for Christmas. I am happy with the WiFi, but improvements are always welcome. Using 5G instead of confusing letters is a good idea. How high will they go with the G series? Maybe in a few centuries we will be up to 145G.