You can do day trips with 1 or 2 kids in a CRV type vehicle. But once you do overnight trips, the amount of stuff you have to bring grows exponentially and that's when the minivan is helpful. Stroller. Play-pen/Pack-N-Play. 3x the normal amount of clothes to account for getting peed/pooped/puked on. Bottles and formula or jars of baby food plus utensils. Do you need to bring a separate highchair/booster seat? Training potty?
Yep, we had to play tetris packing for a week trip this summer.....and my mom had to drive separate. Did similar trip in the fall adding in cold weather gear and we all rode in the van. We went a yr with 2 before sizing up but spent half that time trying to get a van.