In music, form (or architecture) is as important an element as melody, harmony, rhythm, etc. Perhaps the most important!
Music today doesn’t need to employ classical forms (e.g., sonata, rondo, minuet/trio) but whatever the architectural design, it should accomplish the same purpose – namely moving along a compelling musical story.
The forms so common in classical music became so because they achieved that with their balance of statement, transitions, development, recapitulation, closure.
Personally, I find that kind of architecture sorely lacking in much contemporary music. Just my opinion, but many composers writing today seem to lack basic skills in counterpoint and formal structures. A lovely sound fabric or exciting rhythm or interesting melody is not enough.
