Originally Posted by cova

Exactly. A door plug can pop out if the bolts fail. Did it have a good seal? If the seal was bad - could have put more stress on the bolts. Again - I think the fuselage design of where the fake door opening is - if unused could play a part.

A plug door gets the benefit of cabin pressure and helps to seal the cabin.

I would not blame maintenance - they are not going to remove seats and interior panels to inspect bolts. Maybe they will now.
Long term these plug panels may be an issue. Boeing may have to redesign and retrofit to make it a plug door (instead of door plug).

Or maybe airlines will need to remove seats and make this a real emergency exit door.