Just more evidence that WotC is completely disconnected from the fan base. They aren't even familiar with colloquial terms used by the community.
As an old, graybearded, get-off-my-lawn guy, I'd prefer the tabletop version to be the unmarked form 'RPG,' with computer RPGs, live-action RPGs, etc, being marked to distinguish them: E.g. 'cRPG.'
I'll grudgingly use 'ttRPG' because the kids these days need baby-talk to understand me.
I'm pretty consistently on the
'just because we don't like WotC doesn't mean every time they blink we have to explain how it's an affront to our sensibilities' and the
'we are not the adults in the situation unless we show it to be true*,' sides of things, so it's not surprising that I disagree with this. However, in this case I think my objection is we're trying to
police the
language of others to the point of looking for ways to declare it to be someone else actively doing something wrong.
And no, affixing clarifying prefixes to your acronym is not a thing that makes it baby-talk.
See?

In spite of the addition of the extraneous "TT" at some point in the last several years, RPG still works and everyone still knows exactly what it is, unless you're in a context where people think you might be talking about computer or console games too.
That's the situation for which the additional letters were added in the first place, yes.
To be clear, you're decidedly not wrong. It just seems a tautology that a clarifier is extraneous in situations where clarification is not required.
Putting on my entertainment medium-war gloves, we were first.
This is true. I'm just not sure what it shows. First-to-claim doesn't seem to be a strong principle for language. If it were, we'd still be calling fans of Star Trek 'Trekkers.'
TTRPG isn’t my favorite acronym, but the distinction it makes is a necessary one in a world with many millions of computer RPG players, and geez, adding two letters for the sake of forestalling at least two paragraphs of utterly pointless and repetitive back-and-forth is an easy win.
Agreed. And that's why I used the Star Trek example above. I've seen multiple fans of the original '66-'69 series bemoan that it has become 'TOS'* (usually with something like "it was 'Star Trek' until all the rest of this came along"). And, well, yes -- it is clunky. But it's a whole lot less disruptive than any conversational derailment caused by someone not understanding what's being discussed.
*and even George Takei IIRC bemoan that the 2009 movie got to be 'Star Trek' because the first movie was 'Star Trek the Motion Picture'
I mean, those are all true, but the real reason I use RPG is because we were using RPG for literally decades (with CRPG to represent computer or console) and sometime in the last five years or so ago, it seemed like literally everyone started using TTRPG all at once like a school of fish.
This becomes a case of dueling anecdotes/personal experience, but I recall a much more slow and drawn-out adoption of the term. I recall it as early as the late 00s*, and not just in places with newer gamers (also places like Dragonsfoot and Odd74 and other places). Then, slowly over the past 15-20 years it has slowly increased in usage. Not sure what might explain the different experiences.
*side topic: did we all agree that these were "the aughts," and, if so, when?
I find the trend somewhat bizarre.
Bizarre in that people are distinguishing table-top rpgs from other rpgs, or bizarre in the perceived watershed of it being adopted?
I don't think I need to justify using the same acronym that I've been using since the 70s or 80s and which was still the commonly used one at least forty-five years later.
Who is asking you to justify your acronym usage? I think the most likely pertinent question is-- have you used the term RPG and there been any confusion about what you were referencing? If so, it might be because you and the person you are discussing it with (who is not the person you were conversing with 45+ years ago) are not aligned in shared terminology. On the other hand, if that situation does not arise, then there doesn't seem to be a problem.