Its not about everyone needing to be Morrison-level. He didn't do anything so out of this world that only a writing savant could follow up on it. Pak managed just fine. That's not insult to Pak in the slightest, but he doesn't quite have that high concept, out there style that Morrison does. Yet he followed the foundation just fine. More than fine in fact as I felt before the crossovers started in earnest, his run was beginning to rival Morrison's. They each had their own styles but each followed the same Superman. You could clearly see and feel the linkage. Is Morrison better than most with Superman? In the current crop in the business, yeah, he is. That doesn't meant the foundation he had laid down was so complex or too intelligent to be worked with or anything of the sort. So there's nothing telling about not many writers following up on his successful run other than either most writers they got just aren't that good, at least not in the sense of understanding this character and his world, the editorial staff hamstrung them, or a little bit of both.