In order to accommodate first person as a viable, competitive option in your PvP, you should allow for a player's field of view to scale all the way to 180. Most will stop at 90; some might go quake-pro and set thiers to 120. Since third-person is fully functional this will in no way facilitate an unfair advantage. It a uniquely important setting in multi-player games.
It's a major feature for PC gamers, and if it's not included in ESO you will be condemned for that.
I don't have much personal interest, but it's something I have observed as a PC gamer in the past as a consistent outcry and I feel it is valuable feedback because even large companies have managed to screw basic stuff like this up. When that happens PC gamers tend to take it personally as an insult, the feature is considered standard and not including it implies the PC version was an afterthought to a console game; whether that be true or not.