Many people believe that graphics in games are very important. Different games have a different palette of colors. Games that are more aimed for children like, for example, online Dora tend to be more colorful. On the other hand, games that are designed for adults tend to be more gloomy and darker.
It is easy to notice whether a particular game is aimed at children or at adults. However, most gamers play colorful games from time to time. There is something attractive about playing a game that is bright and colorful. There are also games that are gloomier, but are very popular as well. I cannot imagine playing them all the time, but the overall atmosphere in them was different: dark and mysterious. I think that if game developers want to introduce darker graphics, they should feel free to do so. However, they should realize that most children might not want to play such a game but they might prefer to play online Dora instead. You should also realize that if a particular game seems too dark for you, you can usually increase the brightness in the game settings.
Overall, different players may prefer different type of graphics. It seems that there are is a market for both colorful games and more gloomy ones. I, for example, am one of those people who prefer colorful games that can be played online such as many Flash games that can be played on the Internet free of charge. If I could choose between a colorful and a darker game, I would always go for the colorful one. After all, all I want to do after a day at work is to relax in a positive atmosphere doing something fun. I like to be able to look at colorful graphics rather than look at something that it very dark.