While I prefer just playing on the default difficulty, I'm not afraid to lower it a bit when I'm experiencing enough trouble that it hampers my enjoyment. I've got too many games in my backlog to be tied up with a boss that deals out pure bullshit.
In fact, I rarely play any games on a harder difficulty because in almost all cases, a higher difficulty setting doesn't increase the challenge, but just the bullshit. When enemies become damage sponges and your character becomes about as resilient as a wet paper bag, it's not fun, just frustrating and time-consuming.