that does not follow. a constraint is a constraint - musicians will make the best songs they can given constraints. most 4 minute songs are good. the issue is that they then become the only songs, and longer songs are presented as per se bad; this greatly limits miusic. genres that don't get radio play have always ignored that constraint, such as all the metal albums people are referencing or my own love of math rock. a lot of the songs i like tend to last in the 5-10 minute range, more a result of genre and just liking staying on a good song without gaps from loops then sone insistence that a particular length os good music.