i think Nintendo dodged a bullet by naming the series after Zelda because since Link is just the default name and he can be given any name players want then the moment you give him his name the game becomes Legend of Dumbutt or Legend of Retard or whatever other stupid names people come up with.
I know the reason! Its because in the very first Zelda game, Link didn't have a name, he was just a nameless protagonist. That's why putting in the name Zelda gets you the second quest and not putting in the name Link. Zelda was one of the few characters with a name, and as the princess you were saving was kind of important.
Link didn't have his name until the second game in the series. Thus why the series is Legend of Zelda and not Legend of Link.
Actually, Link always had a name. Shigeru Miyamoto's statements in Hyrule Historia mention that in the first Zelda game, he named the protagonist Link because he was supposed to connect people together and was supposed to spread the scattered energy of the world throughout the ages.
Also from Hyrule Historia:
"Of course, the title of the game wasn't decided right at the beginning. I knew I wanted it to be "The Legend of" something, but I had a hard time figuring out what that "something" was going to be. That's when the PR planner said, "Why don't you make a storybook for this game?" He suggested an illustrated story where Link rescues a princess who is a timeless beauty with a classic appeal, and mentioned, "There's a famours American author whose wife's name is Zelda. How about giving that name to the eternal beauty?" I couldn't really get behind the book idea, but I really liked the name Zelda. I asked him if I could use it, and he said it would be fine. And that's where the title The Legend of Zelda was born." - Shigeru Miyamoto.