Again, just because you didn't like a game doesn't mean it wasn't a success.
-.-
Me liking or not liking it doesn't matter in that equation at all. You are talking about a game being a sucess, and I'm telling you that your parameters for success are rather suspicios, and that you may be seriously missatributing the cause for success of the games YOU like, while having little to no perspective into any factors but the select few you care about.
1) I'm not saying Oblivion was a dumbed down version of Morrowind, and I find it shocking that Skyrim is being called a dumbed down version of Oblivion as "dumber than Oblivion" would make something a thematic screensaver. There is only so much simple you can do, and if someone claims Oblivion is superior to Skyrim he is talking through a large nostalgia filter. Oblivion was nothing special, except if it's the only fantasy game you've ever played, Skyrim can only be just more of the same except whoevers playing it got all it can possibly offer from Oblivion so it seems more shallow than Oblivion did.
2) Oblivion was not "dumb" it was just mostly unimaginative and boring, same old baseline fantasy which gets called "fantasy" for no good reason. The precise word for it is "derivative", I think. But that game didn't sell itself, what sold it was the reputation that the company had for making Morrowind. And that reputation was mostly earned because Morrowind decidedly WASNT cookie-cutter - it's wasn't very deep when it comes to character interaction, and the quests where rather simplistic - but at a time isometric rpg's fully devolved into Icewind Dale and Neverwinter nights kind of deal, games for schoolkids and immagination-amputees, Bethesda delivered something which showed that you could do fantasy in a simple but aestethicaly and visually attractive way. In fact, that's what Bethesda stood for once. And that rep got legendary, because there was very little competition. By the point Morrowind rolled out there was so much cookie-cutter crap (Oblivion/Skyrim of yesterday) that people who didn't give a rats ass about graphics were thrilled.
3) Now, since Morrowind wasn't a very "smart" game to begin with, it had comparatively little ways to screw up. If stuff looked good and wasn't "medieval style eourope" kind of deal, it could get away on charm, graphics and ambience. There's very little writing that could be controversial, there's no companions, the core gameplay is hack and slashy and the system is unbalanced by default as the system isn't so important. You'll max out everythign eventually and all that. Every other game which tried to take the loose concept of a fantastic RPG in non-cookie cutter direction fell apart on technical and development grounds because it's, contrary to what you may believe, harder to pull off. Planescape Torment got saddled with a very wrong engine/interface so they had to rush it and it came out half done. Fallout 2 had the same problem, only it's user imput scheeme was simpler so it aged better. VtM: Bloodlines had a terrible engine and was also came out half-done. Morrowind didn't screw that up as it's much more of a bare bones game, so it came out the way it was ment to come out right off the bat - so at that point TeS were pretty much the only franchise which broke the unbelievably stale mold of how RPG's and "fantasy" presented itself. THIS is where they got the rep for their games being legendary - they actually put something immaginative on the market with the funds that caused any studio which tried to make a decent RPG to fail and not be able to finish the product before release. They did do it by "cheating", as the game is a grindy vacation simmulator, but it wasn't set in Forgotten Realms, so it was a huge breath of fresh air.
4) What happened with Oblivion is that a ton of people bought it thinking it would be a followup to Morrowind. And everybody and their grandma at least tried Morrowind and could see why it was standout - it was very different than anything else. So Oblivion sold a lot more copies than it would've if it was being put out by a random company - in fact, it would've probably been a flop. However, anything Bethesda put out after Morrowind would've been a "sucess". Even Oblivion - a complete opposite of what they were at that point legary for, which is, when you get down to it, just art direction. It doesn't matter if someone liked it on it's own, fact of the matter is that TeS were at one point the byword for "groundbreaking" and "unbelievable" and took an art direction decision strongly towards "bland" and "derivative". Which is why sales figures don't matter the least bit - just about everyone would buy the next TeS game once it came out. Word of mouth on the franchise was strong enough, all the cool kids would've been playing it, and with these big games - if you don't play it you're out of the social loop. In todays terms, if everyone is tweeting or filling facebook with Skyrim statuses, a lot of folks will check it out to see what all the fuss is about. And the TeS series is still living off the old glory it had at the only point when they weren't what they are now. You can't get a refund on games, and you can't tell from the demo if a huge open-world game will all be crap. Heck, you have to put in quite a few hours before you decide that "wow, there really isn't anything here worth my time", and by that point you have to struggle against "allready being too invested" to really give up so you end up playing it to the finish even if you don't like it.
So it's not about me specificaly liking Morrowind, or disliking Oblivion. Those games could've been completely different in many ways, but the situation wouldn't change. Morrowind could've looked completely different - that's the point of being immaginative and non-derivative, as long as it wasn't a cookie-cutter 3rd edition D&D base setting clone, and playable, it would've still been hailed as the best thing since sliced bread. Oblivion, the way it was, a polar opposite, could've also been anything within very strict borders it set upon itself - there were a tons of games exactly like it, baseline D&D 3rd edition setting clones, it being in full 3d doesn't figure into it anywhere. But a company using the reputation of "not selling you an Oblivion" to sell you an Oblivion is just ridiculous. There was tons of shit like that out there at any given point! Morrowind sold impossibly well, what was the point of changing the formula so much? Anything they put out would sell like hotcakes, their rep was huuuuuuuge. So if they've killed the cookie-cutter approach with their previous game, why in the world ressurect it? Guys like you would buy anything with shiny graphics, you're not exactly difficult to please - and they had the formula which gave you guys what you wanted by default and guys like me enough of what we wanted to love them. Why compromise that? That won't pay off in the long run, they'll go down eventually. The guys who were doing "mainstream" "no-brainer-content-only-graphics" things with RPGs before Bethesda got taken out by THEM.
I don't think it's impossible to debate this with me - you just need a bit of perspective. If someone shows that they can put out a product that can please both people with some taste and criteria and people who are just mindless consumers, when so many others have failed, why should I respect them if they ONLY go for you guys?