Greed mostly
The responsibility for the tragedy goes mostly to those that decided to put personal benefit above common sense.
There are countless examples of this, where houses, schools and business parks are built in the direct path of a major airport, either military or civilian. The pilot is simply doing as he's been instructed, and flown to the nearest airport. Not really his fault some dickhead decided to build schools and homes around it.
And the loss of one engine in a twin engine fighter is not likely to cause much alarm, you go home, land and ask the lads on the ground to fix it. As others have said, jet engines are usually pretty reliable if properly maintained, but it does happen and pilots are trained to expect it and deal with it, without panic and unnecessary loss of planes or lives.
He certainly wouldn't expect the second engine to fail, and certainly wouldn't have risked serious injury or death by ejecting unnecessarily over water. The military are not particularly forgiving if you have a habit of ditching expensive planes in circumstances that normally don't warrant it.
So he got the one in a million bad luck chance of second engine failure, and at this point as others have also said, he's now flying a brick. High up or low down makes hardly any difference at all. Maybe it would have missed that house, maybe not. More likely it would have hit another or even that school, and certainly wouldn't have got much further.
Besides he was on approach to land, and that means he's now going too slow to adjust his altitude or change course because he has no power. He does the only thing he can, which was to save his own life. Not much consolation to the admirable Mr Yoon if the pilot dies along with the guy's family, which was the only possible outcome should the pilot have made a foolhardy attempt to steer a plummeting brick away from a residential area.
One thing I can guarantee is that no change will come to the policy of allowing property developers to build in dangerous and stupid places. This will be ignored and glossed over, with the pilot the obvious choice of scapegoat, or perhaps the maintenance crew.
Wouldn't surprise me if more than a few politicians start asking for a full 'investigation' too, with their own suggestions as to what (ie who) this investigation should concentrate on. You've got all kinds of choices ranging from Air Traffic Control to superior officers if the pilot becomes off-limits. The last thing they need is attention drawn to how Municipalities and States decide which parcels of land around airports go to which developers and for what purposes, so don't be surprised if all kinds of whacky and illegal suggestions try to deflect away from that - such as why not land a fully armed and faltering jet fighter at an international airport.