I don’t think there are so many parents who are like you describe – want their kids near by to have them at the supper table. Most of us realize they can’t be tied to Mommy’s apron strings forever, and B”H we lead busy lives so we’re not so lonely without them.
There’s pros and cons to each situation as already mentioned above. As a parent of high school boys who’ve been both out of town and in town –
In a dorm yeshiva, the boy often can grow much more as he is in a seviva where all is focused on learning, not busy with narishkeiten so much, and doesn’t come home and want to run to various stores and eateries, etc. That’s if it’s a strong yeshiva – he’ll come home wearing his tztizis out, take his learning much more seriously, etc.
But then there’s a weaker boy who you really want to keep an eye on him more, see him daily so his “look” doesn’t change without you being aware of it. You are more aware of his bedtime, when he’s on the phone at night (so far no texting), his friends, the devices they may have. Much more aware than you’d be if he was away.