Given that Bitcoin is considered a store of value, can you use a cryptocurrency that can guarantee day-to-day usability? How to go to bakeries, fill up the car, travel, etc? Do you know any coins like this?
^ Why not choose BTC alone?
All you have said above was the usability of BTC and for sure there is more usability that can BTC do but usually, people choose to store value than use it as a currency. In altcoins, they have different functions, you can use them all in one coin only even in ETH.
Sorry but I did not hear any when it comes to payment, only BTC can do and is widely accepted.