A lot of players notice the fact that Game Y is often made by devs that desired to make a good game. And devs wanting to make a good game for the sake of making a good game, and hopefully some cash on the side, is noticable.
Game Y II however is often made with making more money in mind. And when money is the overall goal, the substance is not so important. Just as long as you sell enough copies and make your buck. Many notice this, and its understandable that they get angry.
The differnece, at least to me, is big. I know I have used SupCom2 as an example before (I really hate it, and I know I have made that point to you more then once as well
), but it used the name of the previous game, and thus caters to the fans of the first game. However, when playing it you notice it is nothing at all like the first game. It has no RTS scope like the first one, it makes a mockery of the old expereimental units making them now seem trival, it has a horrible single player mode (worst story and voice acting I have seen in a game), it sells the old expereimentals as DLC in an attempt to milk even more money out of the customers and it has bad AI (it also had very few maps imo). To me it comes off as an atempt to make some more moeny out of the title before it is forgotten, and hopefully make the quick buck as a StarCraft 2 placholder until that game gets released. As a pure tactical game, it was ok enough, but thats it. It added nothign new and interesting. And when marked as something else, people will look down on it.
As for the Civ games, I started out during Civ3, but I liked Civ4 a lot more, it had some changes I liked, and had some streamlines and depth to it that was good. Civ5 however seems like a reduced version of Civ4, with some more pretty graphics and mroe focus on comabt tactics. Civ5 was also released with the worst multiplayer code I have seen and it crashed every time me and my frinds attempted to set up a game. One
should expect multiplayer games to work now a days, and even more so in a Civ game obviously desigend for long term multiplayer (cause lets face it, the AI bots suck).
I have not gotten aorunf to playing Dragon Age II a lot yet, but currently it seems to be the same. Just an attempt to milk more money from the title name (and I think Zero Punctuation nailed that one well).
Then there are the smaller game companies, that live of the quality of their games, and who love their games and want to make them the best they can. Guess thats why I play more indie games then I play big studio games. The quest for the big dollar really ruins it for me, and the games seem cheap and hollow, and tbh I can spend my time better then playing crappy games.
Another factor is expectations. If you make a really good game, and people like it, they will naturally expect the same form teh next game with the same title. Some mange to pull it off, for example Fallout 2. It lived up the the expectation of the Fallout fans, and then some. Same woith Baldurs Gate II. It is also cases of the devs really liking what they are doing, and it is noticable.
So I guess it boils down to something like this: Sequals are often bad because the players have the same expectation from the first game, but the makers often have different goals in mind and just want to milk the name for all its worth.
Of course, there are exceptions, sometimes a sequal just suck becuase the devs suck, or is made by an entire new team of devs with no connection to the game world at all.