It may be easier and cheaper to bring suit using a states constitution than the US Constitution. More likely to be heard by a supreme court too.
State legislators are more likely to abide by the clear words of a state constitution as well. Perhaps because of federal authority.
The states where we have the most infringments tend to not have state protections in their constitutions. There are only six:
They are California, New York, New Jersey, Minnesota, Maryland, and Iowa.
Illinois is quite problematic:
Subject only to the police power, the right of the individual citizen to keep and bear arms shall not be infringed.