It seems very ambitious to try to park a satellite in orbit on your very first orbital rocket. Unless I'm missing something?
Honestly, feels like a concerted media effort to stoke panic about North Korea. Japan and South Korea acted like they didn't know was happening publicly (alarms etc) despite being informed of the launch publicly days before as reported in the media.
They may have known it was happening, but once the launch malfunctioned, they didn't know where it was going.
No, or rather it's somewhat more complicated. Yes there are many popular orbits (or deep space) where that's an advantage, but there are also lots of orbits where it's less so or even outright undesirable such as with polar orbits. Depending on the purpose of the launch in question it may be necessary to cancel out that energy which means it's actively more expensive to have it. Locations far from the equator get less either way and have to take that into account.
Launch safety is critical too as well, nobody wants to have debris from a failed launch come down somewhere undesirable. For civilized countries that's anywhere that might cause damage, but even for dictatorships it'd include other countries they don't want to offend that specific way or alternatively to give insights into whatever they are launching that could come from wreckage analysis (failure in low first stage isn't going to mean stuff burns up like a deorbit). So even when a target orbit would indeed benefit from such a directly easterly launch, a dog leg is often part of it.
Obviously NK is less than transparent about all this but the basic incentives are still there.
Trying to find a joke for that applied to SpaceX/Starship.
39.65974870373334, 124.70613853508173
Edit: Aha I see it, I looked it up and it says it is from Tongchang-ri which is where Sohae is, not Tonghae. This was what confused me.
Little knowledge + too much wikipedia + assumptions = fake news :P