They tried to tell FDR that, but he did it anyway, even if it took the Court Packing Bill to get the USSC to go along with it. We've been suffering the consequences ever since.
At the time, the states allowed it because they were desperate for help - anything to get out of the Depression. What would happen if the states started fighting federal power grabs on Constitutional grounds. I'm not talking about secession. To me, that is like letting a burgular have your home. I'm talking about standing and fighting.