Mir kam die Namensgebung mit sr./jr./III/IV immer wie eine Art Adelsersatz vor,
I doesn't necessarily have anything to do with pretensions of nobility in AE culture. My father was a "Jr.," and he and his parents were totally normal folk. It's just that the parents chose to give their child the same name as their parent (typically fathers and male children, but it could also apply to mothers and female children.)
As I see it, it's typically a way of keeping the family line apparent. My older brother wasn't a "Jr.," but his middle name was the same as my dad's, my older sister's middle name was the same as one my aunts, and my middle name is the same as one of my uncles. My mom's first name and middle initial (not her middle name, though -- my grandmother hated her own middle name) were the same as her mother's.