I would venture a guess that you’re saying this primarily because you had already played Morrowind, which was created when the standards for games’ accessibility were much lower. The popular attitude of that day was “RTFM”, and the responsibility of learning a game was placed on the player, not the developer. As a result, you put a lot of time into learning the game’s complexities because you had no other choice if you wanted to get your money’s worth. Now you feel cheated that new players can enter the series without putting in the same amount of work.
I could be wrong. I’m a programmer, not a psychiatrist! But it seems plausible to me that the problem is more due to violated expectations than a lesser game.
While I don’t deny that Skyrim lacks some of the depth and attention to detail of its predessors, I actually don’t agree that it’s worse for removing the things you mentioned. RPG stats in particular are a thing I’m happy to see go away. Skyrim’s perk-based system of “You leveled up! Now, do you want to ability to do a combat roll, or a chance to behead people?” has a much tighter feedback loop than a classic RPG’s “You leveled up! Now you can do 5% more damage!”
But you illustrate a very interesting point that’s actually unique to sequels: the community expects bigger, better, and more complex; because they’ve already mastered the core mechanics of the previous installment. As a result, if game companies were to actually listen to community feedback when developing sequels, their games would only appeal to an increasingly niche market. See Stronghold 2 for an example of a sequel gone bad with feature bloat (disclaimer: I haven’t actually played Stronghold 2).
Which leaves developers with a very tough decision: they could give into the community’s demands and simply add features and complexity, which would have the effect of alienating potential new players coming into the series (with some exceptions; Left 4 Dead 2 did nothing but add features and yet remained accessible and well designed; Portal 2 primarily added features and replaced a few others. Really, Valve just knows how to do sequels right :P); or they could appeal to a broader audience by streamlining the game and removing unnecessary features that don’t add value to the core mechanics (remember the expression: “Perfection is achieved not when there is nothing left to add, but when there is nothing left to take away”.), but alienating the fans of the previous installments who will complain that the new game is “dumbed down”.
No game can ever go through a sequel-streamlining process unscathed by its fans. Mass Effect 2 has its haters, Skyrim has its haters, Battlefield 3 has its haters (myself included; though not because it’s simplified compared to 2; I have other reasons which don’t deserve to be crammed into a sidenote). Supreme Commander 2 was a unique situation in that it actually turned out as a better-designed game than its predecessor by throwing out virtually everything that made Supreme Commander 1 unique - which had the predictable result of also incurring the wrath of SupCom1 fans and the game failed commercially.
In summary: many games considered to be “dumbed down” are actually the result of developers fixing mistakes in the original design and disappointing previous fans who had grown to love those mistakes - perhaps through a bit of Stockholm Syndrome! The philosophical question is this: should developers continue to streamline their games and make them technically better, despite the objections of their fans?
Wow. That was a long rant that was mostly off-topic (Stonehearth isn’t even a sequel!). Sorry. I also apologize if my post comes across as inflammatory - these are just my unsupported opinions, and I know that some people feel very strongly about their favorite games losing complexity.