Lol I just assumed my game was glitched. Perhaps Bethesda figures IRL you don't have a meter unless you're in scuba gear so they scratched it off the list along with important textures.
In real life you don't have a visual meter, but you are certainly aware of how much time you have left underwater from your body's demand for air. The game's air meter would be the equivalent of this. In real life you don't just wait to start drowning before realising you should probably head to the surface....

Plus if you are far underwater using a breathing spell, you want a bit more warning that it has worn off...
Ah well...