I left at 19 for Uni (after spending most of the previous year travelling) and never went back. But I didn't feel welcome.
I do think being forced to be independent did me some good - I'm slightly scornful of uni friends who went straight home to mummy and daddy's, got jobs and then squatted there rent free until they could afford a deposit - stand on your own two feet for heaven's sake, if you're employed you can make do in a shared house or a small flat until you can earn what you want!
Having said that, I do wonder if this pride in what I achieved for myself is rather of necessity since going home was never an option for me. I never went home to visit without my stepmum encouraging me to take more of my stuff away with me - I felt very strongly she wanted me gone for good. I actually have a very good relationship with her now, as equals. Ironically, my half brother (her son) didn't get out of the house or pay his own keep until he was in his mid-twenties, and she sat for that.
I'd like to tread a middle road with my daughter. I want to encourage and enable herto move out once she's an adult, but to always feel that she is welcome and wanted in my house as family, not as a 'guest'. Not too sure how to manage it tbh. I'm hoping if I give her appropriate responsibility and teach her to take pride in her own achievements and a taste for adventure it will happen naturally. If she does need to stay or to return into her 20s, it will have to be on the basis of her making a fair contribution based on her means as another adult member of the family - I'd lose respect for her otherwise and I wouldn't want that to come between us.
I do think a lot of young people are infantilised these days. Times are a lot harder than they were even 15 yrs ago when I was coming up, but I know people in their 20s and even 30s who genuinely feel entitled to live with parents rent free indefinitely, to be given serious financial help with deposits/mortgage payments/tuition fees for postgrad education or vocational training, and most shockingly to me to dictate whether their parents downsize from their 'childhood home' even when they no longer live there! It's a whole different world to what I grew up with and while I (don't think!) I'm bitter, I do feel like I don't know where on earth these kids get the sense of entitlement they have.