Certain forms of speech can be limited. When it comes to political speech, then there is an issue.
I see nothing wrong with limiting billboards pointed towards advertizing.
Billboards for political reasons might be sticky issue.
I think it was back in the 1930s, 1940s,,, the US congress passed a law prohibiting those huge roadside signs unless they were next to a business. Companies were putting up so many roadside signs in rural highways, they were getting to be an eye sore. I think it was eleanor roosevelt that was taking a drive through the country, got tired of looking at the signs, and asked her husband if congress could pass a law restricting billboards.
If the federal government can pass a law restricting bill boards, why cant a city?