In a nutshell (no pun intended), yes! Weddings can be a very long day and I know from spending the majority of the day with my couples that many of them don't eat until the sit down lunch or buffet. You generally wake up quite early to get hair and makeup done and you might eat a little then but the room is busy and it's easy to forget!
Then the adrenaline and excitement of the ceremony will wear you out plus you might have a bit of a drink on your sort of empty stomach. If you pull out canapes at this time then it will line your stomach as the lunch for weddings is still generally about another hour or two away.
I always make sure to carry snack bars in my bag for myself but also just in case one of my couples needs some food or gets hungry. To be fair though the day goes so fast you barely notice if you have or haven't eaten. So it's a good idea to have some canapes, if not for your guests, then for you!