Saying "How are you as a greeting" in passing

Rant time! I'm a friendly guy and say hi to folks I know in passing if I know them but aren't friends with them. Or, I work at the front desk of an office and people often pass and I'll say hi. Sometimes they stop at my desk or they'll go down the hall to the other department on my floor. Typically in most instances, whether at work, school, etc, we exchange hellos and then that's that.

However, I never understood the point of adding on "How are you?" in a greeting. If that happens, it just prolongs what should be a 5 second greeting if you intend to go about your business anyway. What often happens in these situations is:
Me: Hi.
Clueless Guy: Hello. How are you?
Me: Fine. How are you?
Clueless Guy: Good!
I think it's a pointless greeting so whenever someone says, "How are you?", I just respond with, "Fine, thanks."

It isn't like people genuinely care or want to drum up conversation. I would understand if you're good friends with someone and genuinely wonder what they were up to today, but that usually isn't the case with passing greetings. What if something were troubling me? What are you - a psychiatrist? If I were to start rambling about my life to an acquaintance or stranger, it wouldn't make much sense. It just doesn't matter so just say hi.

The reason this came to mind was because one of my clueless co-workers came into work and I was trying to look something up for someone either on the phone or for another co-worker's work. I said hi to Clueless Co-worker and she said, "Hi, Ypsi Guy. How are you?" I just hate that question. I said "Fine." sternly and went back to my work. She then came to the desk before coming into the office and said something about smiling to show I'm fine or something. Then she said something but I really had to go back to what I was working on. Well of course, I'm not smiling - You took my mind off of the work I was doing and are asking a pointless question!

To end this entry on a funny note - I actually mentioned this pet peeve of mine to one of my other co-workers. Before I told her about my pet peeve, I said sarcastically, "Fine. I'm here aren't I? It isn't like I got hit by a bus or something." Ever since I told her my pet peeve, we have an small inside joke where she always says, "How are you?" and I respond with, "Good. I once again managed to not get hit by a bus on my way to work! =D"

Comrades - Do you guys have any pet peeves?