Post graduation, my daughter lived in NYC and Washington DC – roommates were a financial necessity. She’s now in grad school in Denver, living on a modest grant. It’s enough for a small city studio where she could finally live alone, something she’d love to experience after all these years of roommates. But then she’d have to stop eating out, buying shoes, going to bars, buying shoes, traveling, buying shoes… So she’s “saving money” by living alone – in my basement. That’s been her solution… and I enjoy having her around, so… 
My daughter was very happy to have a small studio apartment by herself after graduation. Was sick of roommates (didn’t really have any good roommate experiences in college - was happiest the semester she had a single studio on campus) All of her guy friends that she graduated with have chosen to live with roommates (not sure if it is only a financial concern since they live in an expensive city.)
Both of mine also elected to have roommates. Saved money and while some roommates were better friends than others, neither rally had a bad experience. That said, they are both pretty easy going and get along well with others. Younger s just moved into his new apartment with his fiancée 2 days ago. He commented that at 27, this is the first time he has not had other roomates
My oldest moved to where she knew no one and rented an apartment. The younger one lived alone for two years and hated it. She now lives with a friend and the friend’s husband. The couple owns the house and my kid pays rent that offsets their mortgage.
My first two live in areas where it is too expensive for them to live without a roommate. They’ve had quite a few over the years. Some better than others, but none of them were horrible. (S just got married, so now he has a permanent roommate 
)
Our third kid (who can actually afford a nice apartment in our city) lives in our basement at a very reasonable rent. He likes being around his younger sibs, and I’m happy to collect some rent from him–while helping him max out his retirement account.
OP here. We went out looking at places in his budget just to get an idea. Once he saw for himself what he could afford he decided to skip on the roommate for now. If after a year he wants to get a roommate he can do that. The conversations have been about how he now will have to make an effort to put himself out there to make friends. There are already a few things he’s interested in joining.
Our kids and friends of kids experience:
Student loans and/or large city living = roommates
No student loans and small town/suburban living = no roommates*
*Unless they have a degree in liberal arts
My daughter needed roommates to afford living in Ann Arbor and got a group of friends together that all worked for or were in grad school at the University. She lived with the same 3-5 guys for 2 years and just recently changed jobs and now lives with her high school tennis partner who bought a house. My son is relocating in a month and is living with another guy the company hired from his university. Living alone would have been too pricey but he did find a place where they each have their own bathroom. He’s pretty picky so at least he doesn’t have to share a bathroom anymore.
There are pros/cons both ways. In some cities though, it is almost a requirement to share housing, especially if there are college loans. I’d say for folks on the fence, try the roommate thing to pay down loans faster and/or start a retirement account. If it doesn’t work out, switch to a solo arrangement the next year.
I didn’t go away to college, but I did live with a boyfriend for several years in college and through law school. From the time I left my parents’ home 2 years after graduating law school , until I had my first child, I never had a roommate. I lived in lesser areas, in smaller apartments and the like because I didn’t want to have a roommate. I loved coming home and being alone after a day at work. After not having that life for 27 years, I still remember how nice it was. I urged my D to live alone after college, but she had 2 roommates the first year, had her own room in a sort of commune the next and now lives with her boy friend and two of his college friends. I think growing up in a large family made her need to live with other people, even though she always had her own room from age 5 until her first year of college and then again as an RA.