A large portion of that has to do with Congress limiting their size back in 1929. It turned the House into a second Senate, undermining its purpose. Without that limit Congress would actually represent constituents because the divisions would actually be small enough to effectively do so. Instead we have districts representing millions of people and others representing just a hundred thousand but with the same voting power. The House no longer represents the population and hasn't for nearly 100 years.

The Supreme Court should have been expanded as the federal judicial circuits did. There should be a Justice overseeing each federal circuit, of which there are 12 now. The precedent was set in 1807 when they added a 7th justice to match the new 7th circuit, and 1837 when it expanded to 9 for the new 8th and 9th circuits, and 1863 expanded to 10 for the 10th circuit. They retracted to 7 in 1866 to limit Andrew Johnson and then back to 9 in 1869 after Johnson was out of office. And it has sat there ever since. That clearly was not intended to be the case, but here we are.