I have a major correction to that long-winded post.  I said "All realistic renders incorporate some form of linear workflow," when I meant all realistic renderers.  Totally diffferent.  The point being that if the primary goal of the renderer is realism, then it has some form of correction in general, just because that's more accurate.  The same way such renderers also have caustics and GI.  It's all part of realistic rendering features.  Realistic renders can be made with renderers that aren't optimized for realism, it's just more work for the artist.

Cage, I could totally be off, but I think the development in Poser you're talking about can't happen.  I don't think GC is hard to use for some people because it's not full-featured or developed.  Again, this is just a translation between renderer and sRGB devices.  I mean, yes, it would be nice if certain nodes that are presently included were excluded, or if you had to say whether an input needed to be linearized explicitly with the default being not.  Color_Math, Blender, and EdgeBlend nodes don't quite work properly without protection from GC when they're fed already linearized input.  People work linearly, so it makes more sense to have most of a material work linearly than have most of it treated as if its sRGB.  That said, I don't think that this makes a big difference in most materials.  EZSkin, which everyone uses now, doesn't have protection from this problem and it works fine and everyone loves it. 

I think, unless I'm misunderstanding, the big problem you're talking about is reworking materials made for regular workflow into ones that work the same in linear workflow.  Unfortunately, that's an individual problem, not a universal one.  That is to say, sure, lots of people who have spent ages developing their own look in shading and lighting have had problems converting that shading and lighting to a new workflow.  Unfortunately, that's not a single problem but a large collection of individual problems. 

Again, I could be totally wrong, but I haven't seen a single answer for that.  I've spent a lot of time studying materials- both my own and others'- and I've never seen a consistent approach or look that could be addressed programmatically.  RobynsVeil shared her many and long experiments converting other people's materials to a more accurate and GC-friendly workflow, and it was always a whole lot of trouble and not much reward.   She's more into other stuff now, and I just wholesale replace materials now (and have for a long while).

People mostly made- and make- materials by eyeballing them.  They tried stuff, saw how it rendered, and tried other stuff.  There's not a consistent node combination or behavior to convert.  It's all a bunch of individual kluges that happen to have created a certain look given what is usually a fairly specific set of circumstances.  In my experience, just changing the lighting would often make them behave much differently.

It might be easier to start from scratch, and make an entirely new version that has the same overall goals than to try to force it to have the same specific look and feel as the original.  It also doesn't make sense to try to use GC to change how renders come out but then try to make the render come out the same as it did without GC.  If you liked how it looked originally, then just leave it and save yourself the effort.  Again, it is all about the easiest way to achieve your own artistic goals.

For the general population to use GC comfortably, the big transition that needs to occur is in content creation, not software. Content made to fit linear workflow needs to be available.  In my experience, stuff that looks good with linear workflow looks just fine without it (compared to materials made for regular workflow, that is), but that's just my opinion.