In a nutshell, because it can. Synthesizers were still something of a novelty in the '80s, so it would have been difficult to create the deep, complex bass soun

In a nutshell, because it can. Synthesizers were still something of a novelty in the '80s, so it would have been difficult to create the deep, complex bass sounds we now take for granted. Furthermore, subwoofers were not at all common; even if someone had made such music, it would have sounded like crap on the car stereos, boom boxes, and home hi-fis people actually used at the time. Subwoofers became increasingly popular through the '90s along with the rise of hip-hop music pushing ever-harder bass, synthesizer technology developed along with the increasing power of computers, and by the 2000s music producers had a new corner of the sonic palette to play with. New genres followed suit.