^It is not compromising Alfred at all to acknowledge that he has a past as a fighter and intelligence agent. That's part of who he's been for decades. This is just portraying a version of Alfred that's a little closer to that part of his past, where it looms larger in his makeup rather than being a part of his history that only occasionally comes up. It's a shift in emphasis, a modulation, not a reinvention.
They turned him from a butler into a hulking bruiser. That tells me that they're either pandering to a childish audience who can't respect anybody who doesn't go around punching and kicking somebody or they themselves can't respect or write for such a character. Let the butler be the butler.
Modulation... hmm. You strike me as being like someone who has perfect pitch. If you transpose the same melody into a different key, they don't perceive it as the same melody because their perception of a note is so inseparably attached to its absolute pitch. But other people can hear the same melody in different keys or arrangements and still recognize the commonality uniting the different variations. That's how I approach fictional characters. To you, any modulation in the specifics of a character makes them a different character, whereas to me it's just a variation on the theme. I've always enjoyed variations on themes, the thrill of recognizing the common pattern that underlies two phrases that initially sound different.
I'm not musically inclined, so I don't know what any of that means.
If it means that I would in most cases create a new character rather than change an existing one beyond recognition, then, yes, you're right.