Specifically, when does a kid wearing footie PJs seem a little odd.
If you’re 35 and have pink footies and love them, I don’t care.
You forgot to add Never to your poll. That would’ve been my vote.
That would be “11+ (what age, if ever?)”
Honestly? When they start growing so fast that you couldn’t keep them in footies. There’s more give to the regular kind.
I’m 75, and they’re still nice on winter nights.
I said “5” although it’s nothing I’d ever be particularly strict about.
My reasoning is that I put the toddler in footie pajamas to help ensure that he stays warm on cold nights and to help him stay comfortable trucking around the house when it’s chilly. Once they’re old enough to reasonably take care of that themselves (stay under the covers, put on slippers, etc) then most of my reason for buying them goes away. Especially since they’re both less flexible than regular jammies – if you’re hot, not much you can do besides change out of them completely – and as Zsofia points out they’re less forgiving for growing kids.
Never. Why would this ever be an issue?
Too old for what, exactly?
I remember there was a fad for footie pajamas for teenage girls when I was in high school, it was the kind of thing you would wear to a slumber party. But wow, they make your feet really hot, so I think that was a short-lived thing.
As long as they want.
I don’t get it. They’re PJs. You wear them at home. Who cares? I wish I had some footie pajamas!
Isn’t that how furries start? 
you say that like it’s a bad thing! 
When they’re old enough for grade-school, knock it off.
I’m just remembering that Xmas morning chapter in A Christmas Story and thinking it’s really cruel to do that to a kid.
–G!
Back in college, I about wet myself laughing when I was at a friend’s house and saw his roommate’s girlfriend wearing a set.
I got my first set last year at end of season clearance, so maybe January??? Wore them a few times on the coldest nights, they were great.
I bought my partner a pair when he was in his early 40s, because he was always complaining about cold feet. I wouldn’t wear them, because I can’t stand sleeping with anything on my feet.
Boys, age 7.
Girls can wear them at any age.
“He looks like a pink nightmare!”
I’m putting 5 mostly because I hated pajamas as a kid and the ones with feet were even worse. I was sleeping in my underwear as soon as I got old enough to realize I could just take the stupid pajamas off.
But, really… it’s like the garish and multicolored socks my wife wears to bed. If you can live with the shame of even owning such an item, don’t let age stop you from wearing it. 
On a hot humid night. If there is any danger of heat stroke or heat exhaustion, these “footies” should not be worn. Other wise, meh, who cares.
One of my sisters has worn them at night for her entire life. Her life, her choice. Why should anyone else care?