There's definitely a market for 22mm tanks. The iStick Pico is a very popular mod and it can't take 24 or 25mm tanks.
Absolutely there is a market for 22mm /23mm tanks.
Pico and Pico Mega are very popular here in Germany, and anything bigger than 23 mm won't fit on the Picos.
And many users here have a eVic VTC Mini. Technically you can screw a 25mm atomizer on it, but it looks ....ty, most owners of a VTC mini will also prefer 22 or 23 mm.
I never really understood the fashion of the 25 mm atomizers.
I am a big fan (and frequent user) of the original 23 mm Augvape Merlin.
On the merlin22, i miss: the genius liquid control of the orginal Merlin, and the juice capacity. I think i won't buy the Merlin22. I see not gain over the original Merlin but some loss.