Current era.
Technology enabling music production at minimal costs and exchange of ideas on a scale never seen before.
We just lack the filter of time to see the great things being produced.
I've discussed with musicians who were active during the famed 70s. Crappy shows with antic amplifiers and inexistent monitors, music found and exchanged via worn out casettes copied from late night radio, said radios filed with talentless imitations.
Once past the great acts we remember today because time has filtered the crap out for us, it pretty much sucked. Not to mention the lack of easy transportation to go see the shows.
There are demo tapes from the era so bad that even the most desperate garage band 10 years ago wouldn't have dared ppt them on their MySpace.
There's truth to this, but the biggest change IMO is work related for musicians.
Coming of age in the late 70s, there were many musicians who made a decent living from gigs alone. Some bands were in residence at a gig for years at a time, five or six nights a week. Band leaders were local celebrities.
Even schedules like that were a decline from earlier. The live music scene has been disappearing since the advent of recording. In the thirties, bands of 20 members could make money. By WWII, big bands were out, all of the classic jazz bands were small eg quintets. Now there are only a fraction of the venues that there used to be, and the pay hasn't changed.
That change in work has affected the quality IMO. There's a great deal to be said for grinding out a show night after night, responses vary greatly and bands can get unbelievably tight and responsive. There's also the issue of having to learn certain tunes or beats to please people, granted there's always schlock, but you get in the habit of noticing what gets a response and what doesn't.
American music, which has changed the planet, developed the way it did for two reasons: one the confluence of African rhythms with European instruments, notation, and harmony, and two music was entertainment. But it has less opportunity or room to ferment, and in that sense music is worse off.
OTOH, the technology today is vastly superior. I take my iPad to a gig, and so have access to dozens of books, as well as any charts I create myself and I can search them all in a second. One little keyboard costing less than $700 is as good as an entire rack of gear. And I'm not even touching recording technology.
OK I'm off my soapbox....