Why are small block sizes better than big blocks?

I am trying to understand why big block sizes are bad. I get that it means the blockchain file size is much higher which is a barrier for the layman to run their own node, making it more centralized. But in the future (10-20-30 years), 10-100TB hard drives and other large storage solutions will become so common and cheap in our smartphones and laptops, that everybody would be able to support larger block sizes. Am I missing something? Apologies for the ignorant question.