I even had a professional mechanic, one that does exactly specialize in Toyotas, but all of whom in the shop own Toyotas of various ages, turn to ACC and leave it there overnight, instead of pushing the button. Yes, mine is worn enough the key comes out in whatever position as well. When I went to pick it up, the battery was deader than a doornail. They put a new battery in, at their expense, and away I went.
I even made up a sign, to hang on the steering wheel, describing the correct procedure in turning off the key. ALL the way off
I did it as a joke, sort of. The mechanics at the shop were like "Yeah, yeah, real funny...", but they laughed as much as my wife and I did. They're actually a great bunch of guys, over-all.
They had one...sheesh! I went to pick my Runner up once, and he had left all the vacuum lines off, put the power steering pump on wrong, put the valve cover gasket in upside down, globbed Ultra Copper onto it to try and stop it leaking, and couldn't fit the acorn nut gaskets, so he piled up some washers under the nuts to make them fit, and stuck a screwdriver into the sidewall of one of the tires. They fixed everything for free, and fired the guy. I'm glad I look under the hood before I drive it the first time any day!

Just my little experience with the "key button". Not to mention a truly 1/2 A$$ed, alleged "mechanic". Heck, I'm a profession Radar Technician by trade, and I'm a better mechanic than that guy!
Pat☺

 

Well, if your key and lock cylinder were working like they were supposed to be and not worn out, that wouldn't be a problem.

I am not 100% sure on the purpose of the lock button, but maybe it was an early attempt to prevent you from completely turning off the ignition while driving, which would lock the steering wheel and cause the vehicle to crash. That is just my best guess. It is kind of like how we have to lift up on the door handles if you push down the lock button before closing the door, otherwise the button pops up and unlocks the door.

As the other's have said, many Toyotas from this era had these buttons. My 2 Wheel Drive automatic has one as well.

 

dang yer a smart feller. sounds like a dang good reason to me.

 

so why did toyota change it? (the locks). my ‘89 camry doors lock without holding the handle up, unlike any of my 4runners.


also, neither my ‘91 celica nor my ‘97 corolla had the ignition button, yet the corolla required holding the door handle up to lock the doors.

 

Like I said, I am not sure why Toyota did what they did.

I think the "lifting up of the handle" thing was an attempt to get the driver to remember to not lock their keys in the vehicle.

The problem with either of these quirky solutions is once you get used to doing them several hundred times, they are no longer good at preventing you from doing the thing the button or handle was designed for.

My guess for the change to get rid of the button and having to lift up the door handle was because Toyota realized that their solutions were only good for a new driver of the vehicle.

However, I like those quirky features. It adds character to your vehicle!

 

I ended up just wiring a switch inline with the key sensor switch. So now I can turn the buzzer off if I just want to listen to music with the door open.

 

I actually really like that the key can be removed when running. I consider it a feature and find it annoying I can't do it to other cars.

I believe you are correct that it's vaguely related to safety and locking the steering while moving.

My 1987 4Runner had the lift-to-lock thing on the door, my 1988 Pickup did not. I replaced my door latches on the 4Runner with 1988 latches to disable that annoyance. Now I can lock the door from inside and slam the door shut. I've also seen this on Hondas and Mazdas. A coworker of mine called that procedure the "Jap Slap" to lock the doors.

Some Google searching has revealed that the button is found on autos and manuals from many makes and models both new and old. Basically, I can't find any rhyme or reason.