Not sure where you got that info Mud. And since you mentioned the .218 Bee I'll use that as a comparison.
Remington has one factory Fireball load and I see Nosler does too (although you gotta have a healthy bank account to buy Nosler!).
How many factory loads do you see for the .218 Bee that you mentioned?
I believe only WW has that one covered anymore since it is a vintage Winchester chambering....and they had dropped it from their catalog for a few years too.
You are right in that the Fireball isn't much improvement at all over the Bee besides getting rid of the rimmed case adding about 400-500 fps.
Basically, both of those two cartridges are for the most part a handloader's game since there are few factory loads available.
But as a niche cartridge between the Hornet and the .222/.223, they both fill the bill nicely (as will most variants of the "improved" Hornet cases). Maybe not enough people fit into that niche to warrant a bunch of different factory loads...that doesn't mean there isn't a place for the cartridge though.
I still like the idea of .221 as a mid-size varmint cartridge...both because I've used that cartridge in an XP100 and I've also had the pleasure to shoot an older marlin lever in .218 Bee.
Niche? yep Needed? maybe Available? I'm glad you can get a rifle chambered in that power class without getting a custom job or digging around for an antique.
If you live in a heavier populated area...or in my case where the prairie dogs are more skittish due to hunting pressure, you quickly appreciate a little less muzzle blast that doesn't send every dog within a mile scurrying for cover when you touch off a .222 or .223.