Macabre
Your Friend and Mine
You make a good point. I don't mind swearing either but no one likes (or at least I don't) punks who try to act cool and think they're cool by constantly swearing because they're not. I've seen a lot of cutscenes from the game and while he doesn't always swear he swears so much that, like you mentioned in your edit, it loses its purpose and meaning. He swears just because he likes the words most of the time, whereas DMC3 or DMC4 Dante would add in witty comments instead which is much more likeable to me.
Swearing, as with most things, is diminished by saturation. Overuse is a crutch for those poor in wit.