Because being able to run a bitcoin node is more important than buying a cup of coffee with an on chain transaction.

Without decentralization of nodes, and many of them, bitcoin will die.

Also, in short, blockchains don’t scale.

If you double the block size and allow for 5000-6000 tx per block, that still only allows for around 300 million tx per year which means if every person in the US used bitcoin, they would be able to move their money fewer than once per year.