I think it should be considered Homicide in the Public Interest to use lethal force to kill any person who uses that phrase.
Of the literally millions of provocations deserving a response of Homicide in the Public Interest, you choose this topic? WTF??!?
BLAM. He needed shootin’.
Can you use it in a sentence so I can try to appreciate where you are coming from? It seems mostly harmless to me.
Not the OP, but I hear the term used, mostly in TV reporting, where they mention the age of a senior citizen, usually in a human-interest story. “Mr. John Smith of Tinytown, who’s 97 years young, ran a 5K today,” or, a la Willard Scott on Today, “Mrs. Joan Jones of Springfield turns 103 years young today!”
It always comes across to me as twee and a little condescending (otherwise you’d say “they’re xx years old”), but not enough for me to care one way or the other.
It’s a lame expression to try to pretend you’re not drawing attention to how old someone is, a la “I’d like you to meet my grandpa, who is 76 years young!” Bleh. But useful to reveal how lame the person speaking is.
“Is he five feet, six inches short?”
Oh, there are many more. Queue jumping, for example. In one of the Heinlein books, I think… Time Enough for Love, perhaps?
But then again, the libertarian idea that ‘armed society is polite society’ is all very well until you consider the outliers of the normal distribution who are basically psychopaths. The gun homicide statistics for the US vs the UK are interesting in this respect…
Yes, this is the problem with the phrase. (Describing an eight-year-old as “8 years young” might generate some odd looks, but couldn’t be called patronizing.)
Yes, it’s a mildly annoying phrase for that reason. But not one I’d me moved to pit.
It just grates on my ear. As someone said upthread: it’s so twee.
Not a fan of the expression but it’s better than “yold” which apparently refers to people 64-75.
Hey, I’m 66. I’ll accept “spry”, I’ll accept “grizzled”, but the goddamn truth is I’m old!
“Granny, are you spry?”, bad santa.
A word that until now I was blissfully unaware of.
BLAM! He needed shootin’.
Along the lines of the OP, I’m not much fond of phrases like “60 is the new 50” or whatever. Yes, I know the idiom pattern came from the title of a TV show. That’s reason enough to hate it.
BLAM! He needed shootin’.
And yes, I’ll posthumously grant the OP’s point that " … years young" is hackneyed, twee, and a leftover from the 1960s well past it’s “bury by” date.
Eh, over 2 years ago I pitted people who called my daughter ‘a half’ (as in, entering a restaurant and the host/ess says ‘2 and a half?’, so I’m firmly behind this completely meaningless pitting of a completely innocuous phrase. 
I’m 71, and I’ll let you know when I get old. Hasn’t happened yet, and doesn’t look like it will anytime soon.
Also calling someone who’s clearly a senior citizen “young lady” or “young man”.
Unless you’re significantly, obviously older than they are. Which, given Doper demographics, is entirely possible. 
Okay, can we HIPI people who use obscure initialisms? But whet I really came in here to complain about is the phrase “Fur Babies”.
Oh, we don’t have any children. We don’t need them since we have our Fur Babies. [Turns to husband, who’s not paying attention] Babe, show them the pictures!
And couples that call each other “Babe”… it’s rarely said with real affection. It’s usually some half-concealed version of “Idiot”:
“Babe, you’re not following the directions again… We talked about this, Babe…”
My mom is 85 now, and is starting to come to grips with the fact that she’ll be getting old pretty soon now. But meanwhile, she still goes on adventures around the globe a couple of times a year, and walks 100,000 steps every week.