I've had this happen to in the past. I may be cynical but I think most people just don't care enough about cultivating friendships with you, especially post-college. We just become too preoccupied with our jobs, family, obligations, etc. Even when we do have time to connect, we rather just sit in the couch and watch Breaking Bad instead.. too much effort. So yes, OP's thoughts are nice, but in the end, most of us just fall back to old habits.