For a one-time business interaction, it's just words, though, and not ACTUAL interest, so I prefer to not do that dance. I'm not rude, I just don't feel the need to prolong a simple business transaction with fluff that means nothing.
I don't know that I would call social lubricant that serves to recognize that the other person is not a slave or a machine "fluff that means nothing." But rationally, what you say makes perfect sense, and certainly you are entitled to your preference not to prolong interactions.
However, where social conventions are concerned, rationality doesn't settle the issue (that's kind of the whole point of conventions; they avoid case by case rational or merit decisions). That does NOT mean that you are always rude if you don't say "How are you?" or answer "Fine, thanks," if asked. But occasionally, depending on circumstances, you (general you) might be, no matter what you prefer and what your reasoning is.
It's like, some people have perfectly rational reasons for not liking shaking hands -- religious, health, etc. But the social convention in the US is that it is extremely rude, even hostile, to refuse to shake an offered hand. So if for some reason you simply cannot, you need to compensate in some way, so it's clear that you are not rejecting the social interaction, just the physical act. One man I thought was very gracious puts his hand over his heart instead, smiles regretfully, and says, "For religious reasons, I can't shake hands, but I'm very happy to meet you." Similarly, "Sorry, I need to be extra careful during flu season" or "Sorry, I have bad arthritis in my hand that prevents my shaking hands" and the like (some people bump elbows instead). But if you refuse to shake an offered hand only because you just don't
like it, and you don't apologize and offer a plausible excuse like "I've been around kids who have colds; I don't want to infect you," that's very rude.
In my opinion, the same sometimes holds true, albeit at a much lower level, for social greetings, such as in a situation like this:
Store clerk: "Hi, how are you?"
Customer: "Does this come in red?"
To me, that is a little rude and disrespectful, because it ignores the human gesture the clerk made and speaks only to how the customer wants the clerk to serve them.
"Fine, thanks. Does this come in red?" takes only a split second longer.