It may not be necessary, but it CAN be darn handy to have! Last year (London/Paris) it rained nearly every day and EVERYONE had at least 1 backpack/family. It was necessary for ponchos, umbrellas, water, etc. We are going on Imperial Cities this year and yes, we will take at least one along. I don't particularly care for backpacks either, but they can hold additional clothing if you should need it.