Well, he wasn't just a comic relief character (SPOILER)he's someone who's been in every game and finally got his chance to be a co-star. Weddings are a beautiful part of life, and it was a nice setting to end it with, considering so much of this game was about the high and low points of life - getting old, have it get in the way of your goals (can't crouch-walk for too long!) and watching that person age and not be able to do the things they used to.
Also, about Dumbledore exlains it all - (SPOILER)good metaphor, but I was glad to see it happen, to finally have a real interaction with Big Boss as old Big Boss from legends of yore (Wtf does that make sense!?). Yes, it was drawn out, and after a while it seems like he's just repeating the same nonsensical 10-to-1-to-0-zero becomes one!!! one becomes one hundred!!!) still it was a chance for David to make peace with his father, again, another beautiful part of life. So many games are these ridiculous adolescent power fantasies, THIS GAME IS ABOUT REAL, YO!!!