I have no problem with calling Bill Clinton, Bill Clinton. He called that himself.
I have some problem with calling someone/thing with a name that was pushed from the outside, and was not endorsed by that someone or the creators of that some thing. Say, Wikipedia does not call photocopiers "xeroxes", it mentions "xerox" once in the lead of the "Photocopier" article, and afterwards, photocopiers are only called photocopiers. (And so when you google "xerox", it'll tell you about Xerox the company, not the type of machines.)
And I'm strictly against of calling a thing with a name of a similar thing, which was not even endorsed. That's not useful at all. That's confusing. Perhaps I wouldn't be too wrong if I called that "relabeling" of AK with "AK-47" in the Wikipedia article, a lie. Because that's the thing with lies, they are often hard to keep straight. So throughout the article, its editors can't even figure out - what exactly do they call "AK-47"? The real thing, what Kalashnikov called AK-47, and all its different issues? Or that, and AKM? Or the whole AK family? The answer to that can change in different points in the article.
And I totally understand that people want to call it AK-47. I wouldn't even bring that up if they explained that in the article's lead. Like, "this is an article about AK-47, but what you probably wanted to read about, is actually AKM, here's why". But they don't even do that - not in the lead, at least. Why?
Perhaps because Wikipedia article's leads are used for Google search. Google is actually a major contributor to the Wikimedia Foundation. These leads are shown in SERPs, and they are probably used for Google's machine learning shenanigans elsewhere. Wikipedia is the biggest array of structured, easily-readable information in the world, and Google uses it.
Perhaps, that also was one of motivations behind the "use the common name" rule in Wikipedia, and the adamancy of the Wikipedia editors to use it in this particular case, even when it doesn't make much sense. Because when the average user googles about "ak-47", he doesn't want to be lectured about the differences between AK-47 and AKM and whatnot. He only wants to know about that thing that, as the myth in the media goes, was made by Kalashnikov in 1947, was all sold throughout the world, and has not changed ever since. And it's also on Mozambique's flag.
Because lecturing users is bad for Google's business. So maybe, this is an example how Google's interests made Wikipedia lie.