The first-person mode is still apparently in early development so there’s not much to go on right now, although HYPEX notes that the new viewpoint would be a great fit for Zero Build Mode. However, it’s worth noting that the first-person view hasn’t been confirmed by Epic Games yet, so keep that in mind.
Fortnite is known for its third-person viewpoint, which is crucial not only for its gameplay, but also due to the fact cosmetics play a huge part in the overall experience, so players want to see their character strutting their stuff. A first-person mode wouldn’t allow this, obviously.
Fortnite update 3.58 was recently released for players to tuck into, and is a major patch for the battle royale title as it ushers in support for Chapter 3 Season 3.