Citing your own subjective assessments of other writers decisions doesn't really advance your case, you have to look at it from the POV of the writers. Beechen and Hein..thingie both wrote what they felt they should be writing, and stuck to that. Do I think it worked? Hell no, but THEY did.
Busiek chose to use Nemesis, is it the same take on Nemesis as Hein-sisname had been using and Gail inherited, not quite, nor would I expect it to as they are three different writers.
I would have a lot LESS respect for Busiek if he either radically changed Nemesis personality halfway through the story for no reason, or mysteriously dropped him with no explanation as to why. He's done neither, he's stuck to his own guns and his own take on Nemesis, and I can't fault a writer for choosing to do that, though I can of course, disagree with the results of the choice they made.