I don't agree with the idea whatsoever. It completely defeats the purpose of playing in the third-person perspective. Applying a first-person FoV to 3PP totally defeats the intended purpose of playing in the third-person. With that being said, if this is as big an issue as everyone is making it out to be, then rather than going through the troubles of adding a feature like this into DayZ, you'd be better off just removing 3PP in its entirety. I mean, really, 3PP gameplay is not even broken, so I'm not even sure why there is even any discussion when it comes to "fixing" it... An advantage that everyone has access to is not an advantage, nor is it an "exploit." I can't think of a single third-person shooter in existence that utilizes a feature even remotely similar to this. And it's not due to the fact that it's never been thought of before, it's due to the fact that it's a bad idea and completely defeats the purpose of 3PP. If you don't like third-person, there are always hardcore/veteran servers available. Nobody is forcing you to play in 3PP servers. You can't fix something that's not broken in the first place.
