well it just makes it better. and some people like better and more realistic graphics. and i'm not saying its better than mario,i'm just using mario as an example cuz along with zelda its almost about the same time of age (only a year older) so i'm not saying anything bad or comparing it to mario. so stop saying that its because mario has more products,is older or because its a more kid friendly game.
You are comparing it to Mario. You're saying that they are about the same age, that's a comparison. You say people know Mario but don't know Zelda, yet another comparison. And that is the reason why Mario is more known. He made a big impact when he released in Super Mario Bros on the NES. Ever since, you had 2 more sequels, another game on the SNES, a big hit on the N64, a party, racing, and sports series etc. Mario gets more advertisement and way more games then The Legend of Zelda does. Mario is a household name, everyone knows him because he made such a huge impact and because of this they keep on using him to bring in the money. Just because people know Mario doesn't mean that they play his games or are fans of him at all. He's just like Superman, Mickey Mouse, etc. Nintendo takes The Legend of Zelda more seriously and doesn't whore him out like they do with Mario. It may seem that many people around you don't know of the Legend of Zelda but they probably do. They just don't care to remember it or know what the name of the game is but if you refresh their memory they will remember. It's happened to me many times with the people you least expect to know what The Legend of Zelda is. Mario is the type of character all forms of gamers and non gamers know while the Legend of Zelda's fan base most likely comes from serious gamers-hardcore gamers. Then there are the people who know it but don't care for it. It's all about how they handle the series, You have Mario on this hand getting all sorts of games and advertisement and Zelda on the other hand coming out out every 2-5 years with little advertisement. And yet, both series sell very well. The fact that both series are still alive and kicking shows you that its known and has many fans. But for some reason it seems like the people around you don't know it (That seems to be the case for most people for some reason).
And realistic? What's realistic about The Legend of Zelda? Nothing is.