Many have complained about iOS’s on-screen volume indicator obscuring a large central portion of the screen. Not a problem for audio sources but it is painful for video.
It makes sense to make the volume control very prominent so users who are running into audio issues can get things going. So a system-wide change probably isn’t needed but during video? Argh…
Some apps (e.g. Youtube) implement their own “video-friendly” version of the volume adjustment UI and its such a much nicer experience. Usually, it’s in the form of a line across the top or bottom of the video.
Will Apple ever make the change?