Edit: I should say I think that once you have a core of fans you should always cater your game for them, any additional along the way is just from spreading fame. Not to fundamentally change everything to cater for new people
This is a fallacy. A
huge one.
To give an example - I am a huge X-Men fan. Obviously, when I heard they were making an X-Men film back in 1999-2000, I was extremely excited. I had wanted an X-Men movie my entire life. It came out, it was worth the wait, I loved it. Then I heard they were making a sequel. I was just as excited, and I was just as happy when I saw the movie.
After
X2 released, I became very active in the online X-Men films community, following the production of
X-Men: The Last Stand, and since its release, the productions of the films that followed that. There has been much criticism on the interwebs about X-Men 3 and Wolverine. I happen to love both of those movies, although I do recognize shortcomings. However, one thing that is common is always hearing that Fox should "listen to the fans" and "follow the source material"...
Which is nice in theory.
But impossible in practicality.
Which fans? Which source material? I have read the Dark Phoenix Saga. In many ways, I
do believe that X-Men 3 follows the original storyline, and even the changes made can find some precedent in the original material. But which material do you consider? There are 50 years worth of runs, numerous different titles and alternate takes. The fans themselves are divided about what makes the X-Men the X-Men. So who does Fox cater to? Or, instead, do the film makers just have to make
their vision of the material? It is the latter. Ultimately, the film makers just have to make
their vision of the film, and it's up to the fans to like it or not.
Now, let's apply that to Elder Scrolls.
I think it's fair to say that I am a "true" fan. I have been with the series since the release of Morrowind, it quickly became my favorite game of all time, and remained as such until Skyrim took the crown. My top 3 all time games are Skyrim, Morrowind, and Oblivion. While I don't have huge experience with Arena and Daggerfall, I have gone back and downloaded them and played them a bit.
I feel that Skyrim is an improvement in virtually every way over Morrowind. Yes, there are some things missing from past games, but I believe even
more was added, to make the game even deeper and more complex.
However, many people have a different view on that. They feel that Skyrim has been simplified, and is not as deep as Morrowind.
So which fans does Bethesda cater to? Do they add in all the Morrowind complexity, and isolate fans like me who think Skyrim is a vast improvement? Do they go the Skyrim route and isolate many of the Morrowind fans? Either way, you are not catering to a portion of the fanbase's wishes and desires for the game.
Or ultimately, do they just have to make the game in their vision, and leave it for the fans to decide?
How can you cater to your core fanbase when ultimately, you don't have one because your core fanbase can't even agree on what makes the games great?