All true.
But “I was mistaken” has a LOT of the same tone as “mistakes were made”. IOW, those mistakes were both inevitable and unattributable to any incapacity on my part. They happened, they weren’t caused.
As you suggest, this is not as a matter of dictionary definitions and formal grammar. But at least IME/IMO it definitely is as a matter of idiom.
I had a boss that would storm into the bullpen when something had gone wrong, and when someone inevitably made an excuse, he’d bellow “Can anyone explain the problem without using the passive voice?!?”
It really doesn’t have any of these connotations inherently in general usage. This seems to be something you’re bringing to the table yourself.
In other words, he would be passive-aggressive over the passive voice.
Either you don’t understand the connotation of the phrase, or its generally understood meaning has changed since its origin, and I haven’t kept up (which is entirely possible).
In 1988 the first of a series of ads for Oldsmobile came out with the tag line, “This is not your father’s Oldsmobile.”
The Olds brand, dating back to 1897, had come to be seen as rather staid and boring, and the campaign was intended to persuade younger buyers that the new models were sportier and more exciting than the ones their fathers had owned.
But the implication was not, as you seem to feel, that Dad was dumb for buying the old ones or that they were inferior products. Olds would hardly want to suggest their older cars were bad, only that the newer ones had up-to-date features and were more fun to drive.
Did it work? Apparently not.
Ironically, many fans of the brand say that the declining sales were in fact caused by the “this is not your father’s Oldsmobile” campaign, as the largest market for Oldsmobiles was the population whose parents had, in fact, owned Oldsmobiles and that by going away from the traditional vehicles that Oldsmobile’s brand was built upon, lost many loyal buyers and put the brand on a collision course with Pontiac and Buick, which led to internal cannibalization and a downfall from which it could never recover. Oldsmobile’s final major ad campaign had the slogan “Start Something” in a last-ditch effort to market to younger buyers at the turn of the millennium.[40]
The brand was discontinued in 2004.
I remember the ad, but there have been several other campaigns using the phrase which have shifted the meaning a bit.
Not quite the same phrase, but there’s Progressive’s whole “Don’t Turn Into Your Parents” campaign.
See also the familiar “Call me Joe. Mr. Smith was my father” cliché. It’s part of this whole idea that’s been floating around in the zeitgeist for awhile now, that the most horrible thing that can happen to anyone is that they grow up.
Thank you for pointing this out. Hmm, maybe I’ve been conflating the two phrases.
(I remember an article in the Horizon hardcover periodical from when most baby boomers were teenagers. It ended with a certain amount of schadenfreude about the fact that the teens would inevitably grow up.)
As witness the T-Mobile ad campaign in which the Veruca Salt song from Willie Wonka and the Chocolate Factory has transformed from a condemnation of self-centered brattiness into an “empowerment anthem”:
The worst:
It is to laugh.
The most pretentious 
The most ineffectual
The most frou-frou
“Cuz growing up is awfuller than all the awful things that ever were” (1954).
The fact of the matter is that is the most useless string of syllables ever used, edging out in point of fact largely on the basis of being more useless syllables.
At the end of the day…
I take home my hard-earned pay all on my own. 
The first time I heard this was from a neighbor who’d just moved in (from South Africa), and as he started sanding his garage, he said “At the end of the day, just wanta have a nicely-painted garage, eh?”
I was so impressed that he was going to get the whole thing done that day!
Check Post #13.
I’m on mobile and posts aren’t numbered anymore. It’s a minor annoyance, but an annoyance nonetheless.
I’ve been seeing Facebook ads for Kelley Blue Book pop up, with vehicles described as having respectable or top-notch “driving manners”.
Does that mean the engine doesn’t make burping or farting sounds, or dribble oil on your driveway?
When you push that thing in the center of the wheel, from under the hood comes “FORE!”
Meet-cute is an utterly revolting phrase, and nauseating concept, that I only heard about in the last year or so.
From Wikipedia: “In film and television, a meet cute is a scene in which the two people who will form a future romantic couple meet for the first time, typically under unusual, humorous, or cute circumstances.”
Anyone who uses it in conversation should be banished to do development work in the Canadian Arctic or road maintenance in Montreal.