Whether it's spelled McEwan or McKeown, I would have no idea of how to pronounce it. So I agree that there's no improvement in the alteration.

Many years ago, I worked as an attendant at a public pool. One summer we were ready to close and catch the bus home, except that there was a forgotten five-year-old to deal with. Given the neighborhood, she probably had a long, hard=to-pronounce name of Polish derivation. She couldn't tell us anything of herself or her family except that she was "Denise."

That was when I decided that family names should be recognizable, pronouncable even by the littlest members, and spellable by the general public.