I don't think that describes the long-term trend in game design. I think the first couple decades of RPGs were designed by and for a very particular type of person that loved complexity for complexity's sake (which was me, back then). But over time designers realized that while all those rules and options and weapon tables and spell lists and talent trees were like crack for a certain personality type, none of it actually contributed to the gameplaying and storytelling. All it did was keep RPGs a niche market for that one personality type.In the back of my mind there is always that specter of the "simplify a game to make it more accessible to casual players and thus greater sales" incentive that dominates gaming today,
But rules don't have to be lengthy or complex to be rich. Jon Hodgson once used the phrase (although I paraphrase because I don't remember exactly what he said) "simple rules with deep implications".
An example in RPGs is armor (or "armour): in TOR there is no "best" armor, because there's a trade-off to wearing heavier armor, and while the rules are simple an the list is short, the choice of which armor to wear is actually a complex decision. Contrast that with most (all?) editions of D&D, where there are a lot more armor types, and access is gated through proficiencies and price, with some rules on stealth and encumbrance thrown in for good measure....but really the choice is simple and uninteresting: within the bracket appropriate to your class, take the highest AC you can lay your hands on. I'll take the TOR rules any day.
Another example is talent trees in World of Warcraft. For the uninitiated, for the first few years of WoW each class had three talent "trees", where every level you got to spend a point, working your way up (or down, as the UI was arranged) through prerequisites, many of which cost 3 or 5 points, to the better talents. Then one day they changed to a system where every X levels you just pick one of three talents. Every talent was a single point, and there were no prerequisites. The hard core WoW fanbase, who thought they had developed expertise in optimizing these trees, screamed bloody murder. "Catering to casuals!" But here's the thing: these supposed 'experts' were not creating their own statistical models and using secret builds; basically everybody went to the same theorycrafting sources on the Internet and copied what a handful of smart people told them was optimal. So the new system actually increased choice, despite being simpler, because there were more good choices. (The theorycrafting sites updated their content with a lot of "pick whichever one you like the best".)
So while I agree that RPGs have trended more toward simplicity, and I also agree that the result appeals to a larger audience (yes, leading to more sales), I disagree that it is catering to casuals by dumbing the games down. I think in general the increased appeal is because the games are just better. I, for one, enjoy them more.
Except for before-the-roll Hope. That's just catering to stinkin' casuals.