In science, experimentalism leads to discoveries that lead to (what are supposed to be) advancements over older techniques. If this definition of experimentalism holds true for all applications, then, by extension, in music, experimentalism should lead to discoveries that lead to advancements over older musical techniques.
Indeed, musical experimentalism has led to an abundance of technical novelty made in the name of advancing music as a craft: serialism, total serialism, microtonality, chance, I-Ching and magic squares, alternative playing techniques, electronics, electro-acoustics, tape, the new complexity. Yet, it is, perhaps, less than sound to think that music develops as surely as science can, and it is questionable whether or not these new musical techniques have any of which made a significant impact towards "changing music for the better." One could argue that it would be wasteful for a musician to do what has been done already, as it is wasteful for a biologist to rediscover Mendel's discoveries. However, unlike the continuity of development found in science, in art, there is a rich history of oscillation—periods of greater intricacy are balanced with periods of greater simplicity. In music, we don't have quantifiable means of determining whether or not new procedures are producing good or bad results. We only have the test of time. Scientific works become dated; great music does not.
Nevertheless, in its attempt to reclaim public popularity, music chose to emulate the newly popular science, and adopted an idea of scientific experimentalism to achieve that end. Music became advanced and serious much in the same way that advanced, serious science is. Increasingly greater experimentation led to increasingly greater erudition of technique and, subsequently, increasingly greater inaccessibility. Thus, the newly experimental music came to posses great theoretical complexity, and its scientification can, perhaps, be considered complete. So, has it reclaimed popularity?
All signs point to: No. Because music deals with the qualitative issues of life. To the degree that scientifying music has divorced music from tonality and other traditional structural forms, scientifying music has also divorced music from perhaps its most scientific quality—a common language that can be rationally imparted to and shared among a community of interested students. To the degree that scientifying music has dislocated it from comprehensible subject matter and has forced it into obscurantisms of one sort or another, scientifying music has divided music from its most vital and distinctive function—the simultaneously vivid and comprehensive examination of human experience. Tonality and regular forms had been the common building blocks for centuries in western music history, and THE definition of western music has always been "Harmony." Abandoning these elements has led to an unfortunate interruption in the life of this massively rich history in music making. "There is still a lot of great music yet to be written in the key of C major."
Of course, the experimental trend has long since past. Its hey-day could be pegged at the 1950's, with it's decline following in the footsteps of the so-called "mellowing" of so many of its first practitioners. Experimentalism is not dead, but it has become lost in a sea that has since developed so many other approaches to art. So, where are we now?