Assuming there aren't any significant changes to the protocol to allow more on-chain transactions
Why not make a block every minute? Make the reward 1.25 bitcoin so you still average 12.5 bitcoin every 10 minutes. You still get 12.5 bitcoin every 10 minutes but you get 10 times the number of transactions confirmed.
Why stop at a minute, make a new block every 10 seconds, every second, again with a proportional reward to maintain the average of 12.5 bitcoin every 10 minutes? could get a *lot* more transactions processed and more quickly.
In an altcoin? Sure. There are many that have already done so.
In Bitcoin? That's a hard fork. To accomplish it you need agreement from an overwhelming majority of all users, merchants, miners, exchanges, wallets, etc. Getting that many people to agree overwhelmingly on such a change isn't going to happen. It wasn't even possible to get an overwhelming majority to agree to increase the block size from 1 megabyte to 2 megabytes after 7 years of discussion, debate, argument, and attempts. Attempting to fork with less than an overwhelming majority results in an altcoin "airdrop" ("Bitcoin Cash" was a hard fork without an overwhelming majority).
I don't think there has been a successful hard fork change to "Bitcoin" since Satoshi left. I doubt there ever will be.
Here's something to think about...
Is the purchase of a coffee or pizza really an important or risky enough transaction that every full node should be required to store that transaction FOREVER? If not, then why is it so important that people be able to make such a purchase on-chain?