It does matter, though. DC doesn't want Perez or Jurgens reintroducing an important part of Superman's mythos unless Grant Morrison isn't going to do it, because Morrison's take is not only likely to be more creatively successful, it's also likely to bring in more sales.
The problem is that Morrison tends to be a very improvisational writer, so even he isn't sure what he is going to do. You can see it on Batman, as they launch a Batwing title just before they reveal an entirely different origin for the character, and so forth.
Again, it's a limitation, it's just not one that excuses such poor output.