Efficiency isn't even the issue it's maintenance. Didn't the EU ban all Indonesian airlines from EU airspace due to poor safety records?

If much rather fly on a well maintained 737-200 than a 737-800 from an airline with a poor safety record.

Yes but newer more efficient airframes are also less likely to fail. They will not have the stresses of older less efficient airframes. Maintenance is also a huge factor but it you have spent a fortune on new aircraft you do not scrap maintenance. It might also be a clause in the leasing contract. Remember most airlines lease their newer fleet. The lessors will not be willing to have an airframe without any maintenance.

It isn't usually the airframes that fail - this case has nothing to do with the airframe, as far as I can see. Either a tyre, hydraulics in the nose gear or a defective part in the nose gear. Those are all maintenance issues, not design or airframe issues.