I think considering its for BF4 the fx will be fine and it has allowed a much better GPU.
An i5 4460 and H97 motherboard shouldn't come to much more though and the i5 is a more refined chip on a more up to date platform I'd agree, I just disagree that for the intended purpose its worth dropping to an r9 280 to get the i5
The price skyrockets to $900 without rebate, $760 with if an i5 is used and if the FX is overclocked it'll be just as good in bf4.
IF this was to play BF4 ONLY and never do anything else I would agree. But this will surely be used for other games in the future and possibly upgraded, and for those reasons the i5 is the clear choice. The FX use a dead end 5 year old socket. The i5 will be able to be upgraded to the next line of Intel CPUs without a motherboard swap. This is confirmed.
Though it doesn't really look like broadwell is going to be earth shattering and the fact that skylake is out in the same year probably doesn't bode well for broadwell either. A h97 board certainly won't be compatible with skylake. If the budget was bigger, sure i5 all the way.
There are people who literally just play bf4 you know, I know a few myself!