SCOTUS can't just decree constitutional law in a vacuum. They must have a live "case or controversy". A "case" is not just a theoretical question which someone has thought up. It is an adversarial process in which there is an ongoing conflict in respect of which powers of actual effect can be exercised. It may well be that there has been a constitutional wrong somewhere, but without a remedy for a particular "case or controversy", SCOTUS (along with other judicial bodies) lacks jurisdiction to perform any function.It isn't beyond SCOTUS capacity to rule that the judicial bodies of states doing a role the constitutions define to their legislatures is inconsistent with the constitution. What you are saying is part of the multi-step cycle that makes it impossible to challenge election processes no matter how ridiculous they are. They had a case and they could have taken it..
I mean that's not the only way of going about having a Court, but this is something you're going to have to take up with the founders who limited Article III courts in that way. To suggest otherwise would be to again take an extreme anti-originalist position.