Some stations manage to create good spots for their local advertisers (in those cases, contrary to what BigA said, the client is not responsible for producing their spots). But we cannot control the presentation when an agency buys the time and provides the commercial, pre-produced.
The client can work with the station, but the client approves everything, down to the way the announcer pronounces words. I've seen sessions where a client will pound the announcer to read the same bad copy over and over. When the production person gently suggests a different word, the client ignored him. The client is responsible for the content. It's their time, and their product. Production services are available sometimes. Most of the time, we get agency spots, produced outside the station.
That doesn't answer any of the questions I posed which had nothing to do with the creativity of spots, or lack thereof.
See above. Are we 'willing to give airtime to anyone?' The law says we have to accept all advertising that fits our guidelines. I have a friend in Chicago who requires clients to submit ad copy that his hosts read. No jingles or production. Just host reads. Those are his rules. But other than that, money is money.
It really depends on the format. There are a lot of major advertisers who say in their contracts that their spots can't air in controversial talk shows or in music formats with controversial lyrics. That's their choice. So that leaves the station stuck with a certain type of advertiser.