Dad isn't wrong.
Dad isn't right either.
Dad never lived as a commoner, and hence can't understand the worries of lower strata.
Son have lived as commoner in previous life
Son lived as noble in this life
I'd say son have more balanced insight.
Son lived as a commoner in his previous life, in a society completely different than this one. That's additional insight, but it's warped insight that's not actually that useful for living in a feudal society, unless Cain's aiming to become king and then upend the entire society instead of living in it.
Cain's dad is right, though idk if a specific event created to listen to citizens is really that much of pandering to them than him just normally interacting with them (though he also does that). Cain knows this too, after all one of the points he brings up to the guy he's talking to here is about how they buy fancy clothes because they need to maintain an air of status for negotiations, so he should understand how appearing more like a commoner is in direct opposition to that as others will see it as a lack of nobility/standing.
They're a Duke family, not a Baron or something. If they wanna use their lofty status to help the common people like he's saying, not schmoozing too much with commoners makes sense. But then again, manga loves the trope of "princess/prince who always sneaks out of the castle to talk to commoners", so it's par for the course even if I don't think it actually makes the most sense.