People keep repeating that mSat make no sense as you can't send such small amounts but channels are made to handle many zaps before they settle, so shifting with more granularity and not necessarily with less funds than 1sat might make sense rather sooner than later. In other words, it's not to tip 0.001sat but to have an option to tip 3.5sat when 4sat feels too much once sats reach dollar parity.