https://ffxivcensus.com
This is the reference I used. It shows 4.8 million characters in the game with the number of viera being 149,000
Unless this information is out of date, that would make the number of people playing that race as less than 1% of the total population. But even if that number has increased, it's still a comparatively small number of players to the population as a whole, and given the two major issues of the developers having to work with increased obstacles due to COVID and being months behind, the priority needs to be on the things that keep the game making money, namely finishing off the Shadowbringers patches and the next major expansion as opposed to increasing the number of hats one race can wear.
That's not to say I don't think the race should be able to wear hats. I admit the state it launched in was pretty disappointing, but also at this point you know what you're getting into with that race. Also all the work that has been accomplished has been done by people working on it in their own time, meaning without getting paid. So to demand even more comes across as incredibly selfish, and ungrateful for what work was already done by those people without pay to give at least some options. Remember originally Viera and Hrothgar weren't even able to wear glasses, for example. All that was done by people on their own because they just wanted to make the game a little nicer.