This has also seemed like a odd one but more then likely only a few knew that Minato was Naruto's father. Minato as the Hokage must have had alot of enemies considering that at one time. he had a flee on sight issued on him because he was so dangerous. We've seen just recently that Danzo had used his Sharingan when members of another clan wanted revenge and that's why the information was most likely hush-hush. We've yet to see exactly how Minato and Kushina died so there's probably more to it. What's odd is that the 3rd Hokage, Kakashi and Naruto's own Godfather, Jiraiya, neglected the child of one their most beloved friend for a long time. Maybe that's just part of Naruto's character now and the storyline wouldn't have been as interesting or they were looking out for him behind the books but I hope it get's expanded on.