well 1080p has pretty much been the standard for PC gaming for years now, It's not important ofcourse, but it is a bit disappointing you have to choose it or better effects even after the format has been around for a decade now.
I can see difference between 720p and 1080p, it makes the biggest difference the further away you can see.
It could even mean life/death in games like DayZ where seeing other players before they see you is important, since you have long view distances. Guessing what pixels are a human and what are a bush is much easier on 1080p.