If you’re hiking in more mountainous terrain the foot protection and keeping rocks out also becomes important. Non-waterproof hikers aren’t that much less breathable in my experience, at least not enough to warrant the downsides of sandals.
Not to say it’s not okay to hike in sandals if you prefer, but I think there’s good reason to hike in shoes and why sandals haven’t become as popular.
Just in the US and Canada, for those like me who were curious.