Well, I think that women who choose only tall guys are the same as guys who only choose women with huge boobs. They can do that, of course, it's their choice. But... Well, first I think it depends on how important that is to her. If they'd never consider a guy unless he has a certain height, I'd consider that woman then to be very surficial, since things like a persons character are to her not as important as that persons height. It's also quite stupid, because she might have missed the love of her life, only because that person was maybe a few centimeters too short.
In addition, I think that the amount of women in a country who only want tall men says something about the situation of equal rights in the mind of that countries society.
Like, in a country in which women consider men to be superior and to be the natural leaders, there are more likely to be women who want to be the small cutey harmless sidekick, that gets protected by the powerful strong man. In a country in which women consider themselves to be equal, also do not have as much of a need for a man who physically towers above them to remind them of their status as weak property, but they themselves take measures to protect themselves.
Of course, I don't say that all women who want a tall man want to be treated like pets and trophy wifes. But still, seen on a nationwide scale I think that what I said makes sense.
I myself am a few centimeters shorter than the average german guy. Not much. I still have male friends who are shorter than me, and nearly all women are shorter than me as well, so it's not as if I'm constantly raging at the world for being a few centimeters shorter. But when I read, for example, on a dating site the profile of a woman, and the dating site claims that we're the perfect couple, and that according to her profile and questions and everything we fit perfectly together and live in the same town, and then I read that she only dates men of a certain height, then I'd never message her, even if I'd be that tall, simply because she is such a superficial person.