I think the main reason people are so drawn to E1 when there are so many objectively better maps has less to do with nostalgia and more to do with the fact that E1 maps are just so damn comfy.
What exactly makes a map/game comfy anyway, assuming it's not subjective? One pattern I've noticed is lots of warm colors with little splotches of bright colors here and there. Roller Coaster Tycoon and Ultima Underworld also do this.