Things cost money to make. And it's hard to convince investors that they will get their money back. The genius of Kickstarter is that the investors are the people buying the products. When you contribute to a kickstarter you are essentially preordering a product. The make then has the capital to make said product and send it to you while aslo selling the product at retail. The investor get's their investment back in the form of the product they wanted and the maker can go on to make profit on a product that would never have found a traditional investor.
Publishers don't want to make a little money on a little game. They want to make a ton of money off a giant game. That's why Activision pumps out COD games every year, but doesn't invest in indie style games that will at best sell a few hundred thousands copies. If it's a really good indie style game.
Games traditionally are made by developers who sell their work to a publisher who pays for a popular style game to be made so they can make a ton of money, pay the developer some of it and complain that used sales are killing them. Sorry I went off topic there for a moment. Some guy in his garage can make a game by himself, but it's rare for that game to go all Minecraft. Usually they are ignored it's less a business and more of a hobby. Kickstarter gives hobbyist game makers the opportunity to make their hobby into their dream job while at the same time getting the games that niche gamers want but aren't made anymore.
