Maybe if there were some standard protocol for a device to offer controls to nearby phones. (Perhaps HTML-based, but it would be nice to have a more semantic, scriptable layer, perhaps in addition.)

As it is, every device has its own bespoke iOS app and Android app. The apps’ user interfaces usually suck, but you could say the same about the buttons. More importantly, at least on the iOS side, apps need continual maintenance to avoid breakage on new devices or OS versions, ranging from quick updates for new screen sizes to the dreaded 32-to-64-bit transition. But that maintenance is likely to stop being provided as soon as the manufacturer is focused on their next thing, turning the device into a ticking time bomb of future unusability. With an unrepairable device, at least you only run into the problem if something breaks!