Rather than force the player to hold down ALT to display health bars or change the settings to have them on all the time, I think they should make ALT an on/off switch i.e. pressing turns health bars on or off.
There are a lot of times health bars are useful but sometimes they're just downright disruptive (not to mention they're aesthetically very displeasing).
Holding down alt when you need to micro just makes your job more difficult and I don't really see any point to it. There's no downside to making it an on/off switch.