I find it easier to learn a language if the text to speech voice that I'm listening to is male.
Men and Women speak differently enough in pitch that I sometimes struggle to speak words which contain unfamiliar sounds with only a Female voice as reference.
This may sound like a minor complaint or, worse, be seen as some kind of politically incorrect misogyny. But, this issue causes cognitive friction for users and increases the time & difficulty of language learning. Because of this, I consider this a very real pain point that has a relatively simple fix.