I see no reason why it is in the public's benefit for Clear Channel to own a bazillion stations.
Consider that Rush is necessarily profiting from crap they sell on his show, but from people who pay him to rally the lumpenproletariat to his various dubious causes.
The right of a radio station to earn money is secondary to its providing a public service over the public airwaves.
After all, Rush and Clear Channel can rent space on satellite radio with no need to provide a public service at all. And that's what they should do.