Most probably because the nostalgic childhood and youth years of those complaining get further and further away as we all age. ;)

If GOG would still only sell old games it simply would be dead in the water by now. I doubt that this really is your wish.

I don't want for them to only sell old games but I wish they'd sell everything else I own on floppy and CD. Using images of them now. That's not going to happen with all of them but I can still want them. :)

To be fair, there are some people (very few, but some) who would have preferred GOG "die" than make some of the 2014-era changes/dropped principles that they did.