XML was all about encoding data, not computations. It's far easier to understand data storage than computation. Lisp becomes scary once you start computing and having functional/recursive calls. Look at prolog. Prolog's data storage is very easy for anyone to grasp. dog(fido). man(john), man(dave). The moment, you start computing with prolog recursively, most folks throw up and are ready to stick to their procedural/imperative style.

> Why do you think XML succeeded where sexps failed?

Because it was superficially confortable given HTML and its popularity due to the explosion of the web.

Cosmetics are often more important than substantive structure in popularity.

How often do most people write XML?