Too bad their reputation is tied to being a first instrument taught in schools in the US
The reason to do this is so that lip position is no longer important. I can play these instruments, but I've never put in the time to get a good sound from a non-fipple flute. This is also why they're used in schools: you can immediately make a sound, just by blowing naturally.
But in moving the musician farther from the creation of the sound they also have less control over it. You can't really manipulate pitch and volume independently, and there are many more subtle tone choices available without a fipple.
This is one of the key trade-offs in designing a musical instrument. I wrote more about it in a 2012 post: https://www.jefftk.com/p/instrument-complexity-and-automatio...
you clearly have not heard my child playing the recorder.
[0]: https://www.mollenhauer.com/en/catalog/recorders/series-over...