Far and away the most common size for home tables when I was growing up - you don't have to have a 9 foot table to be "serious" about the game - they're popular because of fit and price and people with home tables weren't going to pool halls, if they even still had one, they were playing . . . . at home.
My Anniversary is the 8 foot "pro" or oversized - love it, but I wouldn't hesitate to get an 8 foot table if it was needed for fit. Even when I played on bar tables, if I had a choice I wasn't playing on 7 foot tables otherwise - but sure, if someone plays a lot of league pool on a 7 footer and that's about it, no doubt that is a great option.