Your point is well taken.
That being said, this appears to be a different situation than the scenarios of choosing community colleges despite acceptance letters from highly-selective colleges/universities, as mentioned up-thread, and represents a much smaller difference in costs.
Are the Virginia public universities you mentioned at $11K/year highly selective? Even so, some may respect that $7K/year tuition difference may not be a negligible sum for all families.
While the OP prefers a commuter experience, in general a comparison of tuition only may be a bit of an apples-and-oranges situation: If the community college is a commuter college and if attending the public university would require room and board, the $7K/year tuition difference would not appear to take into account the true cost differences of attending depending upon the proximity of one's residence in relation to the campus.
hope for generous financial aid
Even financial aid which meets "100% need" may include student loans. Typically student loan interest increases the cost of attendance in a manner which is not negligible.
four year college more suited to their needs
I believe the OP stated needs such as smaller class size (personal attention due to being introverted), commuting via public transit, safety (due to young age).
