1) If you're opening up combat with a surprise attack (likely ranged), you can cast true strike the turn before combat to make sure you hit.
I am pretty sure True Strike is considered an attack and will initiate combat.
2) If we're talking about using it in combat, it can be useful for a Sorcerer that can quicken it as a bonus action. Maybe sometimes a Rogue will want to True Strike if it's the only way they can get sneak attack, and their sneak attack bonus is big enough to justify losing 1x attack.
That would be a good use. I want to see Sorcerer implemented.
3) You simply don't have line of sight this turn and don't want to use your action to dash (maybe you're camping a defensible location and waiting for enemy to approach), I guess then it lets your current turn action do something.
Line of sight is required for True Strike.
