Thanks for taking the time to write a thoughtful article of that sort. I enjoyed reading it. I really couldn't find anything to disagree with in it, as my favorite albums are mostly modern ones. I especially agree with your first and third points. I'm always incredulous when the old codgers come out and say there haven't been any good albums in the last dozen years or so. Saturation has always been present in all forms of metal, but time tends to forget the stuff that sucks. With the wealth of resources available (metal-archives, forums, label pages, reviews, myspaces), it shouldn't be hard to avoid bad releases.
Your second and fourth points do not seem to be big problems here.
You should consider maybe doing some revisions and looking to get this published. I understand that you probably didn't include specific modern bands because then people would just discuss your taste rather than the merit of your arguments. Still, people are going to wonder what bands you like, so they can say that they suck, in order to devalue your points.