You are dividing the OGL D&D market into only 2 halves: those books that take the SRD, modify it slightly and create a rehashed D&D (Iron Heroes, Arcana Unearthed), AND those products that add more material that you can take or leave as needed (101 uses for a dead kobold, etc). There is a third kind of product: One that adds a subsystem to the existing game but that requires a slight tweak to some of the core definitions.
I ignored the 3rd type of product because 1) those are the types of products we make (
Honor and Corruption,
Professions, our
Subclass Series) and 2) I like those type of products so I really don't have any beef with them. Those products, I think, make the OGL shine.
I want to write a 4e product that adds a 10 level tier below Heroic and allows for character to grow into being heroes. Can't be done with the GSL because in to accomplish it, I need to redefine and rewrite parts of how classes are constructed. These redefinitions just affect how 1st level works (since you already have some of your class abilities from lower level, you don't gain them at 1st level). I'm out of luck.
I feel for you, because not all of our stuff converts over as well or at all (subclasses for one). However, I have found that some of our products, like Honor and Corruption, will be better as 4th Edition products - smooth and refreshing.
I converted almost all of the hundreds of feats we created over to 4th and found some I will have to leave behind. For me, 3rd Edition organized and revitalized 1st and 2nd edition info nicely. I am quite upset that 4th changes the fluff around so now those 3rd Edition books fluff is also out the window (unless you continue with the old fluff).
Though it might sound like it, I am by no means completely satisfied with the GSL - but OGC is not dead because of it - it is now in hands of the publishers. As of now, I accept the GSL because I want to make 4th Edition products. I also find that I enjoy making 4th Edition products.
I don't have enough pull to make a stand like Necromancer or Paizo or the others. If I don't make 4th Edition products, frankly, I won't sell anything. That is how the market is for me right now even after 5 years of publishing.