Of course, no one is *forced* to wear these shoes, not like bound feet in China way back when. Women do it voluntarily.
Of course, no woman is forced to do so and Maxima is indeed tall enough to get away with flats or at least lower heels without looking like a smitgen, however there is a great deal of social pressure to ahere to "standarts of elegance" and high heels have been a staple of elegant and formal women's attire for a very long time.
It's not so much the height of the shoe (alone) which might force the Hallux Valgus if you have a precondition, it's a combination of too high and too less support. If you have a precondition to get a Hallux Valgus, also full flat might not be the right choice. Best is modest height, up to 2 inch.
And: give the feet support. Fully closed heels with block heel are better than stiletto are better than sling pumps are better than strappy sandals. The worst you can wear (in terms of causing damage to your feet) is sky high strappy sandals. Anatomically formed insole may also help for prevention (there's, for example, gel filled leather patches you may glue into your pumps, which will make the pumps much more comfortable to wear, as they give the foot some better halt - these are also available in a shorter form to glue them into sandals).
Last but not least: change between high and low every other day to always keep the feet muscles "in motion" and strong.
Then again, as fruela said, you may even get it if you never wear heels - then it might be hereditary or just in your genes. People with vertical talus or lower arch are more likely to get it, also.
But I agree that there is also social pressure of seeing high heels as more elegant than ballerinas - at least for younger women, because once you are > 70 years, no one gives a damn.
I never noticed it on Max (the only thing I recall from her feet is bad pedicure/callus). I guess the worst cases of hallux I've ever seen are Naomi Campbell, Vic Beckham and Catherine Zeta-Jones (@POMME: warning! Graphic content! Do not google this information, or if you do, don't complain you had no warning!).