Positional attacks, indicator is bad.

[Rongway]

While you are correct on a technical standpoint, if you want to check your combat log there are external tools like FFlogs or xivanalysis to do that in great detail.

The Floating Combat text has a different purpose, to quickly show information to the player what is happening in that moment, going through the combat log in the game is very tedious.
Also it shouldconvey a feeling of reward for showing a different color when doing the attacks correctly, not punishing for doing it wrong.

Whether you are reading the numbers in a log or as flying text is irrelevant; it is still easier to see in the heat of combat that you missed a positional if you mark missed positionals, not successful positionals. Choosing to mark successful positionals to establish a sense of reward is detrimental to the function of such marking as an interface. It is more important to be able to read quickly that you missed a positional.