Player Characters are only a very tiny fraction of the whole Eorzean population. So even if you had a thousand Miqo'te men in a plaza, they are still pretty rare. This is because besides the visible citizens (the in-game NPCs) there are thousands upon thousands of invisible ones that are not despicted because of practicality (thousands of NPCs in the streets would require bigger maps, it would consume more computing resources, etc). Basically, Player Characters are extremely rare as far as the universe is concerned.
Specifically, however, that doesn't help the problem of 'why' there are a thousand Miqo'te males in a plaza. The easiest solution is to blame the Calamity: it has changed the face of the world, destroying communities and forcing people to work together more than before. This means traditionally secluded societies or individuals will have to venture out to the world. Male population is still low, but you just get to see more males because they had to come out of 'hiding'.
The same principle can be applied to basically everything (at least that I can think of). Why are there so many paladins? Because the Sultansworn are recruiting more to recover their numbers. White Mages? The Padjal are teaching or taught someone and that person taught a bunch of other people. Summoners? An increase of the beastribes summoning their Primals means more adventurers and people rushing to defeath them. And so on and so forth.
Specifically, however, that doesn't help the problem of 'why' there are a thousand Miqo'te males in a plaza. The easiest solution is to blame the Calamity: it has changed the face of the world, destroying communities and forcing people to work together more than before. This means traditionally secluded societies or individuals will have to venture out to the world. Male population is still low, but you just get to see more males because they had to come out of 'hiding'.
The same principle can be applied to basically everything (at least that I can think of). Why are there so many paladins? Because the Sultansworn are recruiting more to recover their numbers. White Mages? The Padjal are teaching or taught someone and that person taught a bunch of other people. Summoners? An increase of the beastribes summoning their Primals means more adventurers and people rushing to defeath them. And so on and so forth.