I haven't used 32bits channels and probably never will. That's not to say others don't need this as it is one of the standard way of working, and yes experiences vary from person to person. Please respect this and never judge based on your personal experience only.
The problem with a camera response is that it's not one camera response across all camera models - quite the contrary, every camera has its own set of algorithms and sometimes they're made different only to make sure the price tag is justified. Camera vendor - same thing, each one of them has a processed look to make sure your clients know what they buy (Nikon and Canon have a distinctive look and it's kept that way artificially to not alienate their customers when introducing new sensors). So what kind of progress is it to arbitrarily impose a certain way of processing rendered images when all we need to customize them to our liking is already there?
I'm all for new tone mapping algorithms, in fact Filmic Shadows was a wonderful addition. I'd only want this if I can get to the old way with a click or a setting in the defaults. Again, the simple solution would be to introduce a 'Make it photorealistic' button to set the parameters according to the algorithm you come up with and let everything else as it is.
As for legacy settings - well, this is a mess. 1.2, 1.3, 1.4, 1.5 all introduced new things that need to carry code from earlier versions in order to render legacy results, and I assume it must be a nightmare to maintain the code.
And as for always-photorealistic-out-of-the-box. That's a holy grail promise you will not be able to hold up to as it always relies on the artist's skills and eye to properly set up a scene, lights, materials etc. How many renders have we seen from top end renderers that are simply crap because some people don't go the extra mile and polish their materials, or actually work on their image to become really good? That's something you'll not be able to overcome with some math behind.
I really don't want to dismiss the idea just for the sake of keeping everything as it is. It's just that it doesn't convince me why it's better than what we have.
I don't get the point about cameras. Yes, they all have different curves, but they all are superior to CG rendered light and shading interpreted in sRGB, that's the issue here. And while the image processing curves of different cameras are there to make already real image pop, in CG, we don't even have that reality baseline, because we display synthetic, generated light and shading through a response curve that is different to a way human eye is used to seeing reality captured through digital devices in form of digital photographs.
The whole idea of the button is problematic in a way that you basically have a wrong way of displaying something and a right way is hidden behind a button. You wouldn't expect any rendering software these days coming with Linear Workflow disabled by default, and finding a button somewhere in the settings that says "click here to enable LFW", now would you?
These days, LWF is simply a standard, and camera response is evolution of that standard. Again, it's wrong to perceive it as an additional option. It's intended to be update of the default.
I also did not claim that this change would make photorealistic images out of the box. What I (obviously) intended to say that whatever would anyone render would still by default be closer to photorealism than with the old workflow. Even if it was a complete noob, who would just put a gray cube on a gray plane and lit it by Corona spherical light, it would still look a bit closer to what this same scene would look like if it was re-made in real world and shot with a digital camera.
What's also important is, that most people do not realize that in order to successfully translate material properties from photos into 3D, you first need to at least roughly match your tonality to average camera response, otherwise it gets really hard to nail the material properties when translating them from photo to CoronaMTL by eye. Even I, myself found it out relatively recently, and ever since that, I start off with Highlight compression at 1.75, filmic shadows at 0.5 and contrast at 2, whenever I create
any scene. And this is the knowledge most of the people do not have. It will just increase their success rate without need for them to actively research it and come to this conclusion, which it took me personally several years to come to. I wish I had known this earlier... No, actually... I wish there was some renderer that would do it for me earlier :)
