To illustrate this point, I will use the example of Soul Nomad, a game I have discussed before. In Soul Nomad, every unit leader has a list of special powers called tactics, which use up the unit's attack action when used. These can vary widely in effects, from area of effect magic blasts, to self-healing powers, to buffs. However, the usefulness of these powers also widely varied. While the attack spells are incredibly useful, I found that I simply didn't use many of the other kind of tactic. In particular, I only used the buffs in the period of time when I was still closing in on the enemy, and I never got much use out of the healing tactics. My decisions came from the opportunity cost of using a tactic.
The problem with spending a turn to buff or heal using tactics was that it often was not a very efficient use of an action compared to an attack. For example, lets assume that a given unit goes into battle 4 times in one mission (not out of the ordinary in some maps in Soul Nomad). If the unit attacks four times, it will do a total of 400% damage, assuming ideal conditions. If the unit instead spends one turn buffing its attack power by 30% (a typical number in Soul Nomad), and then attacks three times, the unit will only do a total of 390% damage. So spending the one turn to buff actually decreases damage dealt if the battle lasts less than five turns (assuming the buff even lasts the whole battle, I was never able to confirm this or not). Spending a turn de-buffing an enemy can be an even worse tactic, if the enemy dies quickly.
While I admit that this is an overly simplified model, it reflects the way a player makes tactical decisions while playing a game like Soul Nomad. It is also worth noting that spending a turn buffing just isn't as fun as watching a character or unit perform a cool-looking attack. Even though there were times I could have gained an advantage in Soul Nomad by spending a turn healing or buffing, I often instead preferred using the turn to launch an attack against an enemy unit. It made me feel like I was actually making progress more.
I think switching some of these tactics over to being a swift action would not have been a bad idea, though it probably would require rebalancing of the game to match. Since the player was limited to using these abilities to only a few times per battle anyways, there would still have been reason to save them for when needed. It also could have expanded the tactical choices of the player, by making the player choose between healing up before attacking and buffing before attacking every turn.
I think the addition of swift/minor actions to video-game RPGs would open up a lot of so-far unexplored design space. I will probably talk more about this topic, and on actions in RPGs in general, more in the future.