A legitimate artistic choice.
The fact that it doesn't conform to the image of Alfred you have from some of the comics is irrelevant. So what if it doesn't conform? You're acting as if this choice....what's the cliche? 'raped your childhood'.
That's not a cliche, that's a dodge.
Re-imagine Alfred if you want, but don't re-imagine me.
In short, if you want Alfred to be some doddering old weakling useless for anything but housework, then you don't know a thing about Alfred.
And there's the crux of it right there. If Alfred isn't Action Man, with muscles and military experience and other macho credentials to impress the kids, then he's a useless and doddering old weakling. It's possible to write Alfred the butler as an interesting and useful character-- it's just not desirable.