- destruction of diversity in radio broadcasting (something the music industry ironically pushed for) via the death of media ownership regulations mid-'90s
Wrong. Radio hardly has any influence on what music people listen to these days.
I'm not sure that's true -- I actually think the ownership regulations have affected the music being produced. I look at it this way: after the Telecommuncations Act of 1996, companies like ClearChannel now could own stations across the country. In order to lower their costs, they would program all stations of a certain genre out of a central location. Hence, in order to get heard on a ClearChannel station, you can't appeal to local tastes and rely on a good set of customers in just, say, the Southeast markets; instead the music needed to be something that would appeal from Albany to Abilene to Anchorage. When a record company is aiming for as wide a market as possible, they're going to end up going for simpler melodies and sounds to avoid turning people off.
So, in order to get airtime across the country, you're going to tend to push rather pedestrian music. I think this is also why record companies have started pushing fewer artists in the last decade -- it's just not cost-effective to do more variety when every single artist needs to be marketed nationwide.
It all stems from the radio ownership rules. Even if radio no longer influences tastes directly (which might actually just be a case of the tail wagging the dog), it doesn't mean it doesn't have an influence on what's being produced.