While the respect is appreciated, I do take exception to these forms of address from students at my institution – for a couple of reasons.
First, the slightly archaic reasons …
In the United Kingdom, The form of address “Sir” is reserved for those, upon whom the Queen of England has bestowed knighthood (or, who are baronets) – but then, it is only reserved for citizens of nations which hail to the Queen of England as their sovereign. Not that it matters…I am not English. So, no Sir!
However I am a citizen of the great nation of Denmark. As such, I am the subject of a monarch (and, given how things are going in several republics electing their heads of state these days, I am the very much proud subject of a monarch, and an increasingly convinced royalist…). Her Majesty the Queen of Denmark awards knighthoods, also – and transposing English tradition, styling me “Sir” would imply that she had made me a knight – which is (of course) not the case. So also there, no Sir!
In the United States of America, there’s quite some inflation in the use of “Sir”, both in military and civilian life.
As engineering students at Ecole Polytechnique are (junior) officers in the French armed forces, a first point of reference is the use of “Sir” in the United States Armed Forces – where it is used (in place of formal rank or title) for when addressing a senior commissioned officer. As a civilian, I am not a senior (commissioned, or otherwise) officer. So again, no Sir!
As I understand it in France, the equivalent form of address to “Sir” is “Monseigneur” – which, today, is used when addressing a senior commissioned officer from the armed forces, but then only in abbreviated form (Mon General, Mon Colonel., etc – except for in the French navy where it’s a faux pas to address a flag officer as “Mon Admiral” … “Because Napoleon”) – which I am (still) not. In France, “Monseigneur” is also used in the long form when addressing member of clergy. Which I am am even less than an officer. So … very much “Non Monseigneur!”.
In civilian life in the US, the most eager use of “Sir” as a form of address is for customers in the hospitality industry – where the only requirement for being addressed as “Sir” seems to be “being male”…. Which I am. But, so far, I’ve yet to have my drink brought to me in a bar by a student, nor have I had my suitcase taken from me in a hotel lobby by a student (and, for the record, I do prefer that it stays that way …). So, absolutely no Sir!
The use of “Sir” carries baggage. As indicated by the “archaic” examples above, it implies deference. It implies that the person addressed is somehow superior, and to be obeyed (as you would a senior officer, or a customer in the hospitality industry), and obeyed blindly. It implies that the person addressed as “Sir” shall not be questioned, opposed, or doubted.
And that’s not how it’s supposed to be at a place of higher learning. As a teacher, I want to be questioned by my students. I want them to accept what I say as true not because it is I who say so – but, because I manage construct a convincing argument. And should I fail to do so, I want them to call me out on it. I want creativity – which, in part, comes from taking chances and going against the prevalent current – and not succumb to mindless obedience.
In sum, the use of “Sir”, to me, is simply the antithesis of what academia is supposed to be about.