Hey man
Thanks for posting your link. But I'm not sure I agree with you in principle (although in practise of course, there a many examples)
This is my point
I can always tell when the melody was written after the music which drastically reduces the note options for melody.
Writing the melody after the music doesn't reduce your note options at all in my opinion. A good melody writer will hear the way the music moves and find a good melody to fit it. A good example of this is Paul Simon. When he's writing with a band, he'll work in the studio with them till they come up with a track he likes, which he'll bounce to a CD. He takes it home and starts to work on melody/ lyric ideas.
I see the problem you're referring to as much more of a problem of attitude. If your band comes up with some music, and you just dive in with the first melody/ lyric that pops into your head, it's probably gonna sound crap.
But if you spend a month working on fresh ideas, nuances, lyrics, etc you stand just as good a a chance of having a great song as someone who wrote the melody and music together. The problem is as much laziness as anything, I think.