Create metric-equivalent font

My personal opinion: The whole concept of intellectual property is inherently misleading. Copyright, patent, trademark and other monopoly rights have different reasons to exist, histories, lengths, global uniformity/variation, etc etc, and have very little in common. It is impossible to reason about "ip" because it isn't a single thing, the concept attempts to link together such disparate things but because they are so different, nothing makes sense. For example:

"a certain German type designer’s high profile sans serif"

I think you mean a certain American software corporation's sans serif, that was made as work for hire by a certain Dutch designer living in Germany. 

Which is to say, I think the concept of ownership is not as simple as some people like to make out, especially for intangibles.

"The dead guys stole all our best ideas"

No need for splitting hairs about terminology. It is not hard to grasp the basic shittiness of pretending someone else’s work is yours. 

… and reusing someone else’s work without permission.

@Dave Crossland 
Do you know how Google and Łukasz Dziedzic navigated IP laws when creating Carlito, a design that is metric compatible with Calibri? 

Miles, perhaps you could ask your friends who were at Ascender, since they created sans/serif/mono metrics-compatible fonts just discussed on TD this month (https://typedrawers.com/discussion/5421/times-new-roman-in-google-docs-android-app#latest) and probably can tell you more than I can

John, surely you know that not everyone agrees to work on libre fonts!  

As a complete visual knock-off rather than only metrics-compatible, Book Antiqua is a different case. (Also, unlike any of Microsoft’s other PostScript-base-35 “compatible” fonts they got from Monotype. All other cases either were metrics-compatible and NOT lookalikes—or in the case of Times, Monotype had their own totally legit original version.)

Of course, Microsoft later licensed Palatino from Linotype to make up for it. And eventually Monotype ended up owning both ITC and Linotype, so they owned all the originals for all the fonts in question, anyway. 😂

I think the concept of ownership is actually irrelevant, for the reasons you indicate: the rights to the font may be owned by someone who isn’t interested in either financially exploiting them via licensing nor vigorously defending those rights. I am talking about fostering mutual respect and mutual prosperity, which I think means actively seeking ways to share the value derived from the things people have made with the people who made them.

It isn’t always, or even often, a question of lost revenue. It’s about entity Z financially benefiting from value derived from something made by entity X (whether or not originally made for entity Y). Entity Z may be fine with that, or may not be, (as may entity Y), regardless of whether the situation also involves lost revenue or potential revenue.

It’s depressing that people tend to see this as a question of whether or not it is okay to benefit from someone else’s work [without paying them anything]*, instead of an opportunity to help that person prosper and share in the value their work has generated.

* Edit.

Aside: Which came first: Times, or Times New Roman? (The history here isn't clear to me.)

I am reminded a bit of one of the very old, very heated, libre fonts debate threads from the early 2010s, when Vernon Adams quoted Andy Warhol:

"I think everyone should like everyone"

One of the reasons I've enjoyed working in the type community for so many years is that it is extremely collegiate. I prefer to often say 'community' instead of 'industry' partly because it is very much a 'cottage industry' overall, and because 'industry' implies a more detached/alienated relationship to the work and one's colleagues, associates and acquaintances. 

But I also don't see collegiality extending to charity; the craft of type design is ultimately industrial, not a hobby activity in the way that say a sport like soccer is. Almost all type is made for customers to solve their problems, within the competitive marketplace of capitalist society. When a customer's problem includes seeing documents switch from one type to another and reflow, an obvious practical solution is to prevent such reflow by making the new font metrics compatible with the old one. Very well established foundries like FontShop and Monotype have sold this solution to various customers over the decades, and the most commonly used fonts in the work are such fonts, so, personally, I see such solutions as well within 'community norms'. 

Who a customer prefers to work with from the marketplace seems to involve many many factors, and the closest thing to any guarantee of behavior is the law - which is both varying per jurisdiction, and why legal rights that form ownership are vitally relevant. Those various laws often exclude restrictions on making replacements from such rights. E.g. in the UK, the 'design rights' don't cover "spare parts". 

So, overall John, it seems like "fostering mutual respect and mutual prosperity" is generally a very good idea, but who considers who else their mutual, and who interprets words and actions as respectful or not, varies widely, so this seems to me to be a moralizing preference fallacy - which only leads to frustration/depression, as you said.