It's just like Aaron said, Disney made the huge mistake of realeasing Aladdin as a movie that everyone is supposed to love and that we'll probable remember it after so long. Sure, Aladdin was a big hit when it came out, but I don't think it would stay on people's minds forever.
Just like the incident that happened to me in music class when I brought Aladdin. Some people were like "Yay, Aladdin!", "Haven't seen it in a while!", "Is this the part of Aladdin and Jasmines' wedding?"
I was like

. I couldn't believe what I was hearing and from that day on, I knew people didn't remember it. And oh yea, let's not forget what my friend said. "It came out on DVD, when?"
I think it's all due to bad promoting and time. There's a whole new generation of children out there who are more interested in 3-D animation. Stuff like "The Incredibles" and "Finding Nemo". They rather watch handrawn animation like Spongebob or Fairly Oddparents and tend to ignore classics. TLK has been able to survive the test of time and it's because is still in people's minds since there's no one in this world who haven't seen it. Yes, it's everywhere/
"Hakuna Matata!" Stranger: "What a wonderful phrase!"
"Prince Ali..." Stranger: "Errr, what? Wait, wait it's on the tip of my tongue."