What would happen if - just hypothetically - Bitcoin had 16 decimal places and not 8 ?
1 satoshini was 1*10-16 BTC.. transaction fee priced in satoshini / byte.
I think fees would come down, but not by as much as 8 decimal places.
Exactly, I think psychology and our limited brain resources would prevent us to use an "optimal" fee strategy (which would be, in this case, to always chose a fee exactly 1 satoshini per byte higher than what we think our competitors would chose). But it could have a small effect.
Apart from that, 8 more decimal places would enlarge transactions - not by that much, but significantly. Simply chosing "sat/kB" instead of "sat/Byte" seems a better strategy.