I see this claimed all the time on these boards like it's the gold standard, but I disagree. Rankings bring better TV coverage. Rankings catch the attention of recruits. Rankings bring more exposure. Rankings bring more rankings (e.g. if we were ranked at the start of the season we certainly would've been ranked within at least a few games of the VT loss). And the longer you're ranked, the more you can move up in the rankings by winning.
Sure, it's not the only thing that matters (I really would have been happy going 1-11 this season if the W was at Georgia), but it does matter.