The completely orange magazine was offered from the factory very early in the life of the Glock 17. It was intended for Police Ranges where training fire would use the orange magazines exclusively - the officer's issue mags being set aside for the training - and thus all wear would be on magazines that would remain on the range after the officer moved on. And too, the only magazines allowed loaded during training were these orange magazines, reducing the chance of training accidents. I myself own two of these mags, and one of the even rarer baby blue mags. They basically are the same late 17-round 1st generation Glock Non-Drop-Free that Glock was making in black. These mags are considered rare and hard to find, being at least 20 years old.
A few years later, some smart person at Glock decided the same effect could be had by merely replacing the floorplate with a baby blue or orange foorplate.