There is a certain amount of arrogance involved when we assume we have the right to familiarity. One of my early mentors, Dr. Louis Goldberg, was the head of Jewish Studies as Moody Bible Institute. He was a humble man, yet he commanded great respect from the Messianic leaders he mentored. I remember, after I earned my doctoral degree, Dr. Goldberg told me I could call him "Lou.". When I told my wife, she asked what she had to call him. I said she had to call him Dr. Goldberg. That didn't go over well, so she called him Lou as well.
Dr. Goldberg taught at a seminar we had, and it was attended by a brash, street-wise man from my congregation from New York. The man kept calling Dr. Goldberg, "Lou." Dr Goldberg pulled me aside and asked me what was going on with this guy. I told him the man had terminal cancer and was quirky anyway, so Dr. G didn't press the matter, even though it was clearly inappropriate.
What makes it inappropriate is the assumption of being on the same level. When it comes to getting a plane ticket, we are all on the same level, providing we have the funds to purchase them. When it comes to spiritual knowledge, we are not all on the same level.
I have long been a proponent of titles as boundary markers, but only when they are earned. When I run across people with unearned doctorates, or who use the term "rabbi" when they have not properly studied, it turns my stomach. It's no better than people telling everyone that they have black belts in martial arts and call themselves "sensei" when they clearly don't deserve the title.
More than titles, addressing people with familiarity implies a level of disrespect, unless permission is given to address people by their first name. When people wish to show their disapproval with what I write here, they address me by my first name. When they use God's name with familiarity, what are they really expressing?