I haven't followed the specs closely. My grievances with bluetooth weren't around audio quality. They were all around pairing, battery life, reliability during use, and how annoying and frustrating general use was. Maybe this all came from 4.2 and a combination of other tech like available chips or better implementation? For whatever reason, not long after AirPods were released I hear competing headphones improved significantly. I know often can take years and suddenly someone comes along with a clever design pattern everyone else implements on top of old hardware or existing specs.