I'd say it adds some tenderness, some sweetness and helps for the "candy" rib style that is very common in competition.
Those comp style ribs tend to be OVERKILL in everything for a good reason - you need to blow somebody's socks off with one bite, so it's important to be robust. I compare normal 'backyard' ribs to competition ribs like this:
Backyard ribs: Milk Chocolate Hershey Bar
Competition Ribs: A block of fudge
If you only get one bite, the fudge is what you want to go for, but if you ate two bricks of fudge you'd probably be sick.
I only do the wrap/butter/brn sugar/etc for comp ribs, not for normal meal eating.