At this moment in my game (JRPG with turn based battles) I have a health bar for friendly characters, but not for enemy characters.
I do however have a number display for how much damage is done from both sides for each action.
The reasoning behind this is to strike a balance between information and tension- the player knows which actions are effective and can therefore make informed strategic choices, but does not know how close they are to winning an encounter, and must gamble on if they should stay longer and fight or flee as their own health drops lower and lower.
I hope this dynamic pays off. It is also a personal artistic choice to have as few numbers and indicators as practically possible so the focus is on immersion rather than math and number crunching. For example I always disliked in the Pokemon games how you could see the enemies' health bar and their level, which always made me feel more like I was "playing a game" instead of supporting my immersion by hiding elements I realistically shouldn't know.