Bitcoin was always supposed to be digital cash. It even says so in the original white paper title.
Where did this myth start that we need to 'let this go'?
It doesn't matter what use cases were described in the original white paper it it has been what 8 years now? Things have changed Satoshi is gone, block size is 1mb, double spending is a thing and easy to do and merchants shouldn't be expected to wait 10 minutes in a physical store. Bitcoin no longer makes sense as a digital cash and never did for in store use with 10 minute blocks.
3 years ago if you asked "isnt 10 minute confirmations and double spends a problem", you'd have 10 people explaining that credit cards don't confirm for days, that double spends are difficult and risky. There are solutions to detect double spending by querying the mempool. Unfortunately these are not effective if there's heavy network congestion since a doublespend can be attempted much later with a higher fee.
It is really sad that we still have a 1mb block in 2017 but it won't last much longer.