Most people don’t have to pick an everything vehicle. We all benefit when we focus on maximizing our division of labor.
Maybe it's because I'm a dad but I can't imagine telling the family, "Roadtrip time! Let's all pack into the smaller car!". When we're taking the long family road trip to the beach or whatever, we always end up with the big car full of boogie boards and pool toys and cooler and beach umbrella, etc. Bigger cars with longer wheelbases tend to be more comfortable on the highway as well.
The folks I know who do the ICE/EV split household like you've mentioned tend to do the opposite. Dad has a small EV for a cheap and easy commute to work and Mom has an ICE (or hybrid) SUV or minivan that gets used for the long road trips as well as daily errands (but Mom doesn't rack up enough miles for the cost of gas to be much of a worry). There also seems to be less willingness from women (at least in the US) to make the switch to full EVs.
A practical plan is a diversion of labor that maximizes the best and most frequent use cases.
Preferences are driven by culture in the short run and by practicality in the long run.
Once we're at the point where a single vehicle and, say, an ebike are acceptable transit options, then America will have already exceeded it's climate goals. To achieve that, we'd likely need density near that of San Francisco (about 1.10 vehicles per household) or Chicago (about 1.12). Even bike friendly cities that are fairly dense, like Portland, have about 1.5 cars per household.
Again, though, the savings from that would be exceedingly obvious for anyone who chooses this path.