I don't have this problem. None of my friends have this problem. It looks to me more like user error of adding people you don't know and adding spam apps than it is Facebook's problem.
Back when Facebook was new . . . the friends that you had were people that you actually wanted to keep in touch with.
That's still the case with me -- I only make friends with people I want to keep in touch with. The friends you have may have changed in character . . . but I find that hard to parse as Facebook's fault.
It seems to me that regular prunings and a less promiscuous friending policy would solve your problem.
Facebook spams you if someone has your email address in their address book. Facebook spams you if someone wants to be your friend. Facebook spams you if someone has a birthday. Almost half of my Facebook spams are in Spanish, and I don't speak Spanish.
And I have six friends in Facebook. Six. I can't imagine how bad it is if you have 100.