The corolla/civic buyers seem to be on a longer planning horizon than the RAV4/CRV buyers. It's tough to compare sales apples to sales oranges when new car buyers on average buy sedans on 10-15 year schedules and SUVs on roughly 5 year schedules.

That planning horizon differential alone is enough to explain why car manufacturers would be greater incentivized to iterate on SUVs faster than sedans and include more features. Iteration and feature differentials will contribute as much to sales choices as "sit higher up" will, acting as a reinforcement in the cycle/spiral towards larger vehicles.

Car manufacturers aren't incentivized enough to lengthen their own planning horizons or otherwise better accommodate "sensible" sedan drivers, and it becomes very easy to pretend they don't exist and chase the short-term profits of the faster cycle time (especially when pushed by quarterly-earnings focused shareholders).