Because the constitution says the states elect the president. That's how it works. In modern times this means the people of each state decide, by popular vote, how their state votes.

You're saying it should be like this because it is like this. That doesn't take us very far.

But they do have a voice, they are an entire level of gov't. They shouldn't necessarily have any particular say in the election of the president.

States "have a voice" in the local justice system and laws, as well as senators.

Making the president of the whole country be elected directly by the whole country would not make states redundant, far from it.