I ask because I've noticed a lack of children in this game, which was something the US version had, but was lacking in other versions.
Was this choice of version intentional?

It's supposed to be the US version as far as I know, actually.
If it isn't, you can patch children back anyway, use NMA's handy patches section.

It is the U.S. version the 1.2 patch removed children from the U.S. version aswell...

If I remember correctly the unpatched versions with removed children had a problem were items disappeared out of your inventory if you walked through a certain door - turns out in the restored version there were 2 kids either side of the door who would pickpocket you - they removed the kids but left the pickpocket code there!

I tested the GOG Fallout 2 on my machine and there are children ingame.

Yep, because it was never an issue with Fallout 2.

So the children in Fallout 1 got removed by patch? Hmm didn't know this.

Technically there never was an official 1.2 patch for the US. The UK and other countries are the only ones that got that. Fans have packaged the 1.2 patch for the US version, however, and I'm guessing that's what GOG uses. If you already have the US version, though, the fan 1.2 patch shouldn't remove the children.
There should be children in Arroyo. If not, download the F1 children patch from NMA. That should fix it.