For me, in the musical, the quality of the singing is all important. I don't want to see actors who can sing a bit
I think that's true for the stage production, less so for the movie. This movie isn't meant to be, and never was intended to be, a perfect replica of the stage show - what would be the point in that? It's a new adaptation, and a lot mroe can be done acting-wise on film than can be done on stage in terms of detailing, so if that's at the expense of big belting singing, then that's fine by me. As long as they're all in tune and the tone of their voices don't grate!