The Slôpglütening is already in full force on DriveThruRPG...
Somewhat counter-intuitively, it is the larger companies who seem to understand the appeal of boutique, human made art as a market positioning tool, while smaller and indie publishers are sort of going full hog on it.
Some of that is about perspective: Fate never reached number 2 status thst I can find, it was always behind Fantasy Flight Games house system games, Warhammer and then Star Wars. For a while it has seemed like Powered by the Apocalypse was The Thijg with the Avatar game even reaching Target...
Eh, it's a pretty obscure flash in the pan, to be honest...but interesting.
In addition to the rules controversy. Which seems to have been intense, GDW made some metaplot Setting decisions that were extremely unpopular, to the point that subsequent Traveller iterations reset the Setting to the...
No. Actually, Traveller: The New Era replaced Megatraveller entirely. It...didn't go well. So much so, in fact, that itnis a pretty direct analogy to 4E D&D.
I think you basically are right thouh: Traveller has a history that parallels D&D pretty closely, a Rollercoaster to an evergreen present.
We can go a step farther: while new variants do get released, Backgammon and Chess are fairly stable at this point. I thinkt he Crearice Commons release of D&D makes wild change to D&D-as-D&D sociological improbable.
Pretty simply a matter of material culture: injection molding was only invented around WWII, and then soon people figured out they could make dice easily in any shape. People.made dice in other shapes throughout history, but cubes are thr easiest to carve. Still the easiest to store and ship...