Please, give us a "Restore Missing Files" Option...

I was 100% worried 2 years ago when I got Endwalker that this topic will soon be brought up.

Since Dawntrail is a pretty huge expansion and eats up a lot of GB, I had to switch from HD to SSD early in the morning after downloading the entirety of Pre-Dawntrail. But as SOON as I try to boot the game, boom, Error: could not locate data files. Please reinstall FINAL FANTASY XIV.(50000).

Wasted not only my own time, wi-fi and money for early access but also my hopes on checking out the "new graphics" that totally not surprisingly is not that great in a lot of people's opinions. So having a button in the launcher that somehow could Restore missing files instead of forcing you to re-download 98GB worth of content would be a God-save.
Especially if they plan to make even MORE expansions and patches. 98GB is not a joke lol I have to wait over 11 hours to even be able to boot my game now.

Don't mind me adding some fuel to the fire but it is frustrating to wait with 5MB downloading every second :3

For this same reason i had two separate folders with FFXIV pre Dawntrailer because i had some bad files that didn't let me play cutscenes from ARR without crashing the game (Example: every Praetorium cutscene would close the game) and if i clicked the restore file thing in the launcher it would redownload the whole game deleting all the contents from one of the folders. My final solution yesterday was to delete all previous installations of the game and download the 98Gb from DT and make a second copy of the game just in case something like that happens again.