I think some of it is the bands like Wolfmother who wear the Zep influence much more clearly than 90's bands did. Bands like Soundgarden and Alice in Chains were certainly influenced by Zeppelin but it wasn't as clear. Mostly because their lyrics were a lot darker and introspective than "squeeze my lemon until the juice runs down my leg". Not that that particular line isn't profound. :)
Always good for a chuckle when we were teenagers.
A woman told me once that her young daughter liked the Led Zep "Ice Cream Cone" song. I searched my memory banks for a Zep ice cream cone reference, and when I came up empty handed, she said, "You know the song--'I come from the land of the ice cream cone...'"!!
That's not Zeppelin, that's Robert Johnson.