I don't follow sports enough to be qualified to answer this question. I am not entirely sure if sports can be a form of art at all.

"Demon's Souls is a good game (my opinion), for an action game with semi RPG elements, some people don't like it though (their opinion). It certainly is not art."

Why not? Is not the way that the ambiance of the world and the strictness of the mechanics combine to create a feeling of dread in the player a perfect example of how games can be art?

Ice skating, if you want to call that a sport, can be an art form. For the most part, just like games, most if not all of it is not art. 

Would you say Moby Dick is a good novel?

Absolutely. It is, in fact, a perfect example of a good novel that is at the same time not a particularly enjoyable novel for most people to read. Even people who like it.

Dread? lol. Despite that 'textbook' definition of art, even if a game does 'affect the senses or emotions' it is still not necessarily art. By that definition Wii sports could be art because it can make you happy to work out.

See, when Moby Dick was released many people thought it wasn't a good book at all. Ironically I think it's quite boring at times because it is way too much to read but that's exactly what makes it such a great book. See? It is a great book because of the things I don't like about it. The same goes for Mozart who only got popular and well liked after his death.

Maybe Wii Sports is the best piece of art ever created but you just can't see it, like it happened to a lot of people with Moby Dick and Mozart

Quality is completely subjective, there is no possible quantifier that can prove something to be quality or something to have no quality without personal bias creeping in at some point.

What you can talk about is perceived quality, so you could say that a critically praised movie would have perceived quality, but not everybody will like it just because some respected people within that industry say it's good. Some of the most highly praised films have bored me enough to never finish them, and I would debate till I'm blue in the face that they are not as good as they are made out to be by those respected individuals. At the same time, I've enjoyed films that these same respected people will dismiss out of hand as trash. That isn't an attempt to draw a line under it by saying that I am right and they are wrong, nor am I saying that that is always the case, as I will often agree with those individuals at both ends of the scale, it is just my individually perceived quality rearing its head, and every now and then it falls in line with that apparently respected viewpoint.

In the same way, you can say that something that appeals to the masses and sells well has perceived quality to more people, as it wouldn't sell that well without some kind of quality. Again, there is nothing to say that those people are factually correct with their claims of a quality product, but you cannot dictate a pre-set list of things that are purported to be quality to them and expect them to go along with it, as that removes all sense of free will and individuality.

If someone wants to enjoy Twilight or something that some people perceive as being poor quality, then let them. I see no gain in walking up to them and telling them why they are wrong to like it. By all means, if you find yourself in a debate about it, explain why you don't like something and keep a level head, but don't flat out tell someone they are wrong to like something. That just makes you look bad.

"Dread? lol. Despite that 'textbook' definition of art, even if a game does 'affect the senses or emotions' it is still not necessarily art. By that definition Wii sports could be art because it can make you happy to work out."

Eating pie makes me happy, but eating is not art. The definition is more complex than simply affecting the emotions.

That is what I was saying, that missing part of the definition, is what is missing from Demon's Souls, thus it is not art.