The Court in FDR's time was
acting very badly, e.g. by not respecting the separation of powers, obstructing legislation geared toward fixing socio-economic issues (this is the proper function of the legislature) based on legal doctrines constructed out of whole cloth (e.g. "economic due process," whatever the fuck that means). Thankfully, the Court
changed its tune, due in part to the influence of
one of our nation's greatest judges. FDR's court packing legislation, while objectionable on its face, was an equivalent response to a Court which refused to stay in its lane. By contrast, Liberals today are upset that the Court refuses legislate from the bench. The Court is not here to obstruct Donald Trump just because you find his executive orders objectionable (It is alarming that 4 of 5 Justices were actually willing to do so). On the contrary, the Court is here to make sure nobody stops Donald Trump from issuing lawful executive orders, just because they may be objectionable to some.
I urge you to read up on the views of one Oliver Wendell Holmes. He's a hero not just for progressives, but for jurists who understand the proper role of the judiciary. To borrow his phrasing, this newfound Liberal affinity for court packing, "if it is accepted, will carry us far toward the end."