This is a tangent of my previous post that got so big I just decided it needed to be its own post.
In my mind TSR will always be thought of as the KINGS of "we know you want X, but we, in our infinite wisdom, will give you Y because, well, me and the 10 guys in this room like Y".
Here's an example of this thinking:
Why didn't every game TSR make use the D&D game engine or a derivative of it?
The AD&D engine might be the most popular engine of all time. Other companies tried like the devil to make compatible products for it and were roundly sued by TSR for their trouble
I am not debating the wisdom of TSR's love of lawsuits- just pointing out that companies were willing to risk the wrath of a notoriously letigious company just for the ability to make something compatible with the best selling game engine on the market.
But when TSR went to make a sci-fi game, or a post-apocalyptic game (which is SO CLOSE to fantasy as a genre that it's totally unfunny) or a western game, they started from scratch and tried to forget D&D ever existed.
I always felt this was a mistake and think it speaks more to designers wanting THEIR turn at crafting a game engine more than it does any burning desire of the market for more game engines.
The success of d20, Hero and GURPs should tell you everything you need to know about how badly people want multiple game engines for tabletop gaming.
For the most part, people find an engine they like, and they NEVER WANT ANOTHER ONE.
They want to use that engine for modern games, fantasy games, sci-fi games, post-apoc games etc etc.