if you ONLY ride down south, only ride Lewis Morris, only ride the race courses or your name is Anrothar and/or you are just
that pimp on a bike, than no, there, is no need for suspension fork on a 29er. however, if you are a mortal, you will both enjoy and benefit from the fork.
here's some real world experience: i rode my mary rigid for 18 months before getting a reba. i had a TON of fun on that bike set up rigid and i really got good at picking lines and moving the bike around. it is fun, that's for sure. but, i have a ton MORE fun with the fork. i can just go faster, i don't get as beat up and i can go faster.
so there you have it.
edit: one more point- to address your height...i recently learned, that i too am 5'8" plus after going through all of my adult life thinking i was 5'10". i am living proof that you can ride a 16" mary.