It's common for action games to afford the player the ability to heal instead of attacking. I even have a bias toward this type of ability - if a game offers me a choice between having more health/attack or being able to heal, I'm very likely to choose the healing ability, even if my balance intuition tells me it's weaker. But this mechanic is actually really destructive to player enjoyment if not implemented carefully. To illustrate, let me talk about the 2005 Revenge of the Sith Xbox game.

In this game, you play alternately as Obi-Wan and Anakin throughout 17 levels comprising more or less the plot of the movie. Either Jedi has the ability to spend force energy to heal. The problem is many-fold. For one thing, it's very inefficient unless you upgrade it, and your force also doesn't instantly regenerate outside of combat, so if you're really playing to win, you'll stop between each fight and wait for your entire force bar to regenerate as many times as it takes to get you back to full health before going on. But that takes so long that if you're not really playing to win, you'll often find yourself getting impatient and going into the next fight with less than full health. You see the problem? The game forces you to choose between having fun and playing well.

Another facet to the problem is that it messes with the level-section model of progress saving that the game uses. Since most levels allow you an opportunity to heal between each fight, if you're patient then each encounter becomes a self-contained challenge... except you don't save after each one. The game is balanced according to the progress-saving model it uses, so the result is that it's very hard to die on most missions, provided you don't get impatient. The only parts that actually gave me trouble even on hard were the boss fights and the rare level with no safe spots (like the Utapau battle). Those were the parts of the game that worked. Unfortunately, they were probably a minority of gameplay time.

A third area the problem shows itself in is the duels. Most of the bosses in the game are other Jedi, who can also heal, so it sometimes happens (especially in PvP duels) that both players are bad at punishing healing, and so they both continue to get away with it, leading to some very drawn-out duels that should've ended a while ago.

For an example of a game that implemented healing in a way that avoided these problems, see The Force Unleashed. In this game, healing isn't an ability you have; you heal by killing enemies. This means it's never the optimal strategy to hide in a corner and heal for a while. When you're low on health, the only thing to do is get out there and fight. It's also very in-flavor since you play as a Sith in that game.