Depends a lot on the related mechanics.
- Health bar is important if health doesn't regenerate, as you definitely want to see how much health you have (because if you don't then you kind of just randomly die which isn't very satisfying).
- if health regenerates, then we can do much more vague health indicators (such as increasing red color many games with automatic health regen do)
- I wouldn't add just a visual gimmick for health, unless it somehow changes how the game operates
In general with UI I'd say, it's not an aesthetic choice, it's more thinking about what supports your core mechanics.