Yes i will for several reasons.
One: i dont like to leave anything unfinished, and i consider not ranking up stopping when i am only part way through.
Two: i think that the game is alot more fun when working towards something. Just sitting around and not getting anywhere gets old.
Three: i like the Prestige. Not the system of ranking up. The actual pride of having done it all again, and putting in that effort to go the extra mile. (even though it is only a video game)
Four: I always liked to have more create-a-class slots. I like to have options so if i dont like how on class is working i can easily switch to the next one. This also allows me to keep my S&D classes set up at all times. therefor when switching game modes i dont have to keep rebuilding my classes.
Five: now that i cannot unlock everything at the first prestige i want to get more unlocks. I like to have plenty of options. And as the game gets stale i like to branch out. Usually i use SMGs, Shotties, and the occasional AR. Near the upper prestiges i like to branch out into LMGs and the occasional sniper
I think that about sums it up.
-note: i have never reached max prestige. I tend to go hard in the first two months and fizzle out as summer draws closer, and then i pick it up again as winter comes again. One of these times i will get there though