While pirates will probably work out a way to incorporate the patch/fix whatever, it's still clever. I think Game Dev Tycoon and Batman: Arkham Asylum both did something similar also. The former made it such that any games output in GDT woud eventually be pirated and the player unable to succeed. In the latter, Batman couldn't activate his glide ability or something at a point in the game where it was required.
I'm very glad that FC4 evidently HAS an FoV slider in game. Frankly if a game doesn't have it I'm not going to play it. Default console FoVs are awful on a PC (Sleeping Dogs is an example of this, Mafia 2 as well). I'm glad to see more and more games starting to have it in game (like Bioshock Infinite, BL2, FC3). It's always a hassle to have to dig through ini/cfg/bin files or find a 3rd party mod/program. And for an FPS especially it's crucial.
Anyway, Ubisoft did something clever. They're still bastards, holding their games back from Steam, putting microtransactions into full priced games, unable to make games that run at 1080p/60fps (despite it being the par du jours on the PC), regurgitating the same game year after year, lying, marketing trickery, review embargoes and forced uPlay. And that's just what I can think of off the top of my head.