I'm willing to wager the reason for the one beat jump limitation with the CDJ-2000NXS is to prevent any buffering issues that would impact performance for DJ's who may use the CDJ's to play a CD since the read speed would be reduced dramatically.
Since this is their flagship product, I'm fairly certain they will implement additional beat jump values with a future update with the caveat being that it will only function when using a USB/External HDD/CPU connection and not CD/DVD.
Keep in mind, these decks aren't even a year old yet so there's still plenty that Pioneer can (and most likely will) do to improve the functionality. I'm sure their high-end DJ clientele has mentioned similar concerns.
Cheers.