tl;dr: Basically, I agree with the idea that newscasters speak in that accent and dialect because there is a definite value in it. I think that your disagreement with others in this thread may only arise from the specific terms you used to describe folks who don’t use that dialect in an informal setting. Heck, that may be a side effect of your own natural dialect.
Well, newscasters do speak in that manner, but that’s because it is the default “middle ground” between all of the dialects and accents available in the US. It’s a pity we have to outsource it to Canadians, taking our national news anchor positions. I have a specific style I try to use at work that is pretty close to the idea of a newscaster. I use that because that is the one that is most likely to be understood by the global expanse of English speaking customers and co-workers I communicate with. My accent is something that I kind of think I don’t have, until a customer asks me “Where are you from? I have never heard someone who speaks like you do.”
And of course when I hear myself on recording when I’m tired or excited, I don’t sound the way I sound in my head. I sound like a character actor in a western. It’s still a weird accent, I’ve had other Texans ask me if I was from (of all places) Connecticut. I also kind of look like a Muppet, so I imagine experiencing me in real life might be either unsettling or fun, depending on your perspective.
Sometimes when I’m tired/excited/irritated, I not only show my accent, but I drop fully into how I normally speak (without cursing hopefully), including tons of colloquialisms. This not only causes confusion in some of my customers, but also my co-workers who are already kind of familiar with how I speak and write through exposure.
For example, one of the calls I completely lost control over when I was young was one where I told a customer “What y’all need to do is, <blahblahblahblahblah>”. That brought tons of laughter from the other end, and comments such as “What, you think we’re fixing a tractor?” After a couple minutes of that, I eventually had to tell them that if they weren’t going to follow my instructions, I’d hang up, and they’d be on their own in resolving their problems. In comparison to me on their problem, they were a bunch of monkeys trying to fuck a football. So, they shut up and followed my instructions. They seemed to try to comfort themselves about their collective ignorance by making fun of my use of language. However, they understood exactly what I meant.
The flip side of this is my current job where I help a bunch of people from a very varied set of linguistical backgrounds. I’m unquestionably in the position of power, and when they don’t understand my advice for either a technical issue or a problem with my use of language they often don’t question me, despite me encouraging them to do so. I’ve often had them come back to me after my previous advice did not solve their customer’s problem and I apologize, and try to clarify what I meant in less colorful language that I feel is less ambiguous.
And in regard to a generational gap, I had to look up “KRK” recently, because all the younger folks kept sending me that in chat. Apparently I’m a funny guy, and internet English is adopting Korean, now. Yeah, that sentence makes me feel old.