While I have yet to sell my first knife to a customer, I have made various kinds of art and sold it since I was in high school. I've done a lot of paintings, drawings, conceptual work, flash art, all kinds of stuff. Every one of them was a piece of me and was signed by me. I wanted everyone who ever saw it till the end of time to know that it was me who made it. I consider knives that the maker designs the same thing. I think as far as burger joints go, the customer is always right and if they have the cash, it's their money. Make it their way. However, when it comes to artwork, that design is part of the artist. It originated inside them and it is a representation of them. If the customer designs the knife and he wants no mark on it, well that's up to the maker, but if the knife from beginning to end is the makers work, it deserves his mark. Asking an artist not to sign their work is an insult. That's like saying, "I like the pretty thing you made, but have no interest or appreciation what so ever for the skill and talent that you possess that made this work possible."
Obviously the military need for a sterile tool doesn't fall into this category. For everything else, that's your work. If the customer doesn't want to give you the credit and appreciation for your skills and isn't proud to show that they have a piece of the craft, then they don't need to be a customer.
Before I started trying to make them myself, I had designed a knife that I asked Ian Van Reenen to make for me. Even in my drawings, his mark was on the blade. I made it clear to him that the skills were his and I was proud to have that represented on the blade. After all, that's why I chose him to make it. That knife design was mine from front to back. I chose the handle material, the pins, the grind, the hardware, everything. Ian made a few small suggestions that made sense and I went with them, but for the most part, that knife came from inside of me. However, it was Ian's skills and talent that made that knife a reality. For his ability to produce that piece of art, I am proud to give him credit on my knife.
Maybe I'm crazy, naive, whatever. I know I'm not yet a "real" knifemaker who sells his work, but this is what I believe. My knives are my knives. If they customer doesn't want the mark, then he doesn't need the steel it's etched in.