"Move files to this directory" — not sure exactly what that'd do (move which files?). But it sounds confusing next to buttons which only change Picard's transient state, but don't actually change your files (loading files into picard, changing Picard's directory browser root folder). Accidentally hitting it would be a PITA, compared to the no big deal of the other two.
Also, of those three, hard to believe anything other than "add" is really a frequent action.
I think I'd rather skip the buttons, and just have double-click add instead of expand folders. But that's definitely a hidden power-user thing.
I may be somewhat weird though, I don't have Picard move my files, ever. And it'd not know to use
git mv anyway.