Yes, cause comments are the worst place to handle that. 

Quite honestly, I suspect "all of the above" would be a potential close reason here.

Lets start with the original question title

> Why have the "black editions" been popular for Windows XP but not for
> Windows 7?
> 

I hope it would not be a stretch that popularity is very clearly a matter of opinion:

And the original question wording that was opinion based (and I hope we agree on that):

> Why is that? Is it because Windows 7 has been inherently more
> customizable? Is it because there's the issue of "what to fit on 1 CD"
> with Windows 7 not fitting on 1 CD anyway? Other issues?

And the new version

> Why - to your knowledge, not speculation - have similar modified
> versions of Windows 7 and Window 8 or 8.1 not been released, at least
> not regularly? Have the people/groups maintaining Windows XP "black
> edition" issued statements about this choice?

They might have been. They might not. It might be due to better or worse copy protection. It could be due to economics, with people in previously poor countries able to better afford copies of windows. Hardware could have changed more slowly. Too broad? Potentially

Essentially none of these elements are something that the end user directly has to deal with. So… off topic (plain and simple). Oh and asking “have people/groups maintaining Windows XP black editions issued statements about this choice?” Learning material recommendation maybe. I didn't even think about that yet until writing this answer. And in any case, that’s not something an end user deals with directly, its almost like asking “Why didn’t Microsoft release Windows 9?” or “Why isn't there an ultimate edition in Windows 10?” 

So, at *this* point, outside of "this is off topic" plain and simple, I guess this could be too broad, deals with the mental processes of "Freelance software repackaging groups" (since of course, we've not come to to talking about piracy), as well as the popularity of this group. 

I believe there’s an analogy to marijuana made here. I don’t know anything about drugs so I apologize for the ridiculously made up names, and non existent strains of weed mentioned here. 

Let me quote something you said in the comments.

> Can you not discuss trends in worldwide cannabis agriculture on US
> news broadcasts because it's illegal to grow it in the US (mostly)?

Lets rephrase that to fit the analogy:

> "Since legalisation of marijunana in notreal state in the US, the
> popularity of XP black has gone down. Everyone seems to be buying
> mainstream, licenced w8 and w10 weed from licensed dispensaries. Why
> is that? Have the growops who used to grow XP black made a statement
> about it?"

And well, if we had a “Marijuana.stackexchange” and by some *weird* coincidence, I was a moderator there… I’d close it as being opinion based, since its a matter of choices made by customers and freelance herbal packaging groups!

Now, lets talk about legality. By its nature, something like Windows XP Black or various distributions like that are infringements of copyright. The act of creating such a distribution for personal use from your own copy may not be, but the moment you put a iso online, it is. Essentially, any question about such distributions involve piracy, and in many cases such a question, even—if it were otherwise on topic—would be closed. This is also the underpinning of our policy on Hackintosh questions (and I’ve answered the rare TOS respecting Hackintosh question!).

I am not a lawyer but to me—as a moderator—this part of the [Stack Exchange TOS][1] is what’s in play here:

> Subscriber represents, warrants and agrees that it will not contribute
> any Subscriber Content that (a) infringes, violates or otherwise
> interferes with any copyright or trademark of another party…

And a question on XP black essentially interferes with Microsoft’s copyright on Windows XP, and is against the [Stack Exchange TOS][1].

Now, lets talk about what might be an acceptable question. Lets talk about nLite and such tools. A question about a replacement for nLite may be on topic for software recs. A question about working out what to remove on an OS install might be overbroad but potentially on topic here. With the limitation that *you might have broken your own install preinstall*, some questions on stripping down and running a stripped down OS may be on topic. 


  [1]: http://stackexchange.com/legal