While most games don't made some complexity in their games, most "true" RPG games in the past have always been prone to getting in the over complex territory which can easily put off players who did want to play the game.
The problem with RPG's of the past remaining "overtly complex" while every other genre improved is because making games didn't didn't cost a miniature fortune to make and RPG were allowed to remain in that niche market demographic. So for a long while, RPG had a very consistent static "feel" that games learned to "expect". And if it didn't sell too well, it wasn't the end of the world for the developer because the game would still have regained most of it back anyways.
Now that gamers are demanding that graphics look better and better, want each NPC having its own voice actor, on top of engine licencing (or making your own) while also needing real "physics"; the price of games quickly skyrocket to more then just mere 'pocket' change.
For every weapon type needing a different 3d rendering for each of the various levels, included unique ones adds time and cost - 2d sprites can be churned out in a day, d3 models, not quite so much.
Every skill needs to be codded and debugged until it works. The leveling system needs to be codded and debugged until it works. The more simplistic these systems are, the lower the price of development the cost is, along with allowing more players to become interested.
Are developers willing to lose 5% of the most hardcoreist of the hardcore PRG's if it means gaining 30% or more of the non hardcore gaming market. You bet their fucking pants off they do. In a way, this is what happened to many of us in the transition of change between ME1 to ME2. Too be fair, people did expected change for ME1 -- just not in such drastic measures.
Now to answer the OP's question, "is dumbing down good?". To be fair, it depends on where you are starting and where you finish up with. Is getting rid of skill that say, only 1% of the gamers population likes "dumbing down". Is getting rid of complex confusing systems that can be redone so its better streamlined, and yet still functional, while only losing a small fraction of its flexibility "dumbing down"?
In some cases, "dumbing down" can be very beneficial to the game play and flow of the game; and there are some cases where a developer and "dumb down" too far. So I vote yes with the statement that that it isn't a blanket across the board "dumbing down is good".
tl:dr -- features cost money -- games today are expensive to make -- RPG's can no longer remain in limited niche markets.