For NYU and Columbia Why X's, what I hear is that they kinda already know why people want them so it might be redundant to add an additional document on this, but if you have a really compelling reason to write one, don't hold back.
They won't be bothered by the 169 if you have a higher score. Right now, you've got about a coin toss chance (according to lsn) at the lower T14. A 173 would give you a solid shot at NYU and Columbia, and a slight chance at HYS and Chicago
As for NYU, it just isn't happening ... is gonna get in to NYU. It is 1000% my dream ... honestly tell me Columbia would be more likely than NYU, but even ...