You can't just analyze from the perspective of a percentage fee, because the blocksize is constrained.

My comment: The blocksize is constrained but not the monetary value of bitcoin. And the % fee is not based on the blocksize (which is limited), but on the monetary value of bitcoin (which is unlimited). It's just like using gold to facilitate global commerce. Many say gold is too limited in supply for the role, but some say, well, just adjust the price of gold (upward) will just do. The same is with bitcoin.

It can become possible that transacting in morsels as small as 1 BTC is no longer possible.

My comment: If that's true, then we can throw out the 8 decimals of bitcoin as we won't be using it soon. The fact that it is well thought out to have 8 decimals is very probably because we will still be transacting in fractions of bitcoin no matter the fee.