As you probably foresaw, you have ruffled some feathers. You often make interesting comments (not just on this thread) and this has been the most interesting thread on here for ages, so thank you!
More on other threads than this one, you have made comments about repetition and/or repetitive structures. Like you, I think I too am very sensitive to repetition. Glenn Gould said that he was not 'overly-fond' of Schubert's music given its (overly) repetitive structures, so I think it ok to hold such views. I can find myself not overly fond of variations or music based on serialistic structures.
I don't know if Nocturnal is a 'masterpiece', but the two things that really make it stand out for me are:
1) As Mr Freitag says, the transition to the theme is a sublime moment. There is a divine passage in Cavalleria Rusticana (and I am not an opera-lover) that gets me in the same way. Likewise there are passages in Nielsen (S. Semplice) and Strauss (numerous) that I simply find incredibly moving; and
2) That (unlike some pieces by non-guitarist composers) it finds resonant spots on the guitar. It could be worth directly experiencing the harmonics on the guitar in person (either by seeing it played live or even by playing them yourself).
Never say Never. These modern works are very much like modern art. Not everyone walks into a room with a Jackson Pollock in it and swoons. I really don't mean to be patronising, but one day, when you are in the right setting with the right performer and in the right mood, the piece may hit you. I have certainly had this happen to me on a number of occasions both with art (Giacommettis) and music (many times). In fact just this week I had an epiphany with Fantasia para un Gentilhombre (not as challenging as Nocturnal). Over the years I had listened to a couple of (in retrospect rather prosaic) recordings of this and dismissed the piece as being not that interesting. However, I listened to Segovia's recording this week, and it is so full of authority and presence as to make the piece speak to me.