Vettori is under-rated with the bat in my opinion. He can hang around, and make a good amount of runs, especially for a tail ender. A few months back, I included him in my World Test XI, as the second spinner and a bowling allrounder who bats at number 7 - that's how much I rate him with the bat.
New Zealand can't afford to do that, because they need to name the extra batsmen, because they struggle as a side with the bat. Their bowling is generally alright, but batting is dire, definitely not up to standard in Test Matches, and won't be able to compete with quality sides such as Australia, South Africa and India, not to mention Sri Lanka and even Pakistan.