Barney:
Your answer is reasonable if I don't have any business sending you email in the first place, or if you don't want me to know whether you've received my message. If that's the case, then I agree. No one is under any obligation to acknowledge a message he never requested, or that doesn't concern something of mutual interest to the communicants...by their own subjective determination. I'm fiercely protective of my own privacy too.
But that's not what I'm talking about. I'm talking about the condition wherein communicants WANT to know whether they've received each other's messages; for example, to keep important messages from falling through the cracks. It happens, you know. Receipts (and especially, the absence of receipts) have saved me and my associates from honest mistakes and missing messages more times than I can count. But if the ability to request and acknowledge receipts isn't even there, they're out of luck...and living with ignorance about the status of their communications.
Besides, every civilized mail client I know of enables the user to set a preference that notifies the recipient that the sender has requested a receipt, and asks whether he whether he wants to honor that request for any given incoming message. If, in your judgment, it's none of my business whether you read my message, you don't have to acknowledge receiving it.
In fact, most mail clients enable the user to automatically deny all receipt requests. Receipt acknowledgment is turned off as the default condition. If you don't want to use it, then you don't have to do anything. The only folks who would even know about it would be those who want to use it.
So, I still don't see how having the feature available is a problem for anyone...but maybe I'm missing something.