My attempted explanation of some of Mozart's and Liszt's differences was intentionally simplified, or I wouldn't compare Liszt's music to a movie script. My point was though that Liszt has more layers, and layers above layers, and hides the low-level stimulus-response type of reactive emotions within these layers resulting in a stronger, broader, more "expressive" structure, but also musically easier to receive and transmit as bigger packets. I think that when we speak of difficulty in music, technical side of it is unimportant because technique is simply what makes playing and interpreting music possible, and in the end when one has achieved technical profoundity, the highest demand arises from musicality - to internalize music as you play it, touch it just enough to allow it to become real in that brief moment in time. Putting technical aspects aside, flawlessly processing and transmitting Mozart is by far more demanding than to throw oneself into a "Liszt mood" and just react to the emotions that the music evokes. I just think that when you're playing Mozart, you have to be more present in the moment, in the music, to tie the notes together, articulate the music seamlessly.
If you're saying that Mozart is easier to play, who are you relating to? If you're playing a Mozart sonata that doesn't much appeal to you, to someone else, and in the end the listener just says "It was nice", do you take it as a succesful performance? Or are you alone a sufficient quantity to relate your music to in order to determine success in bringing out the music? I'm just interested to know, why do you think Mozart is easy to play, and I hope you're not only thinking of the technical side of it.
Topic: 50 greatest composers