I hate not having physical back and so on buttons on a phone, doing away with them a daft decision IMO, though not perfect it is useless without them at moments like I just had where a Google pop-up for some reason had a problem and just left me with a white screen saying "Can't load this page" and no navigation controls and no amount of gestures, etc. would close it... fortunately didn't have to force restart the phone as turning the screen off and back on again so the login appeared enabled me to get back out of it...
I really don't know what goes through developer's minds these days, probably nothing, such poor accounting for continence situations never leads to anything good even if those situations are for the most part edge cases (until they aren't).