Another thing to consider is, that it may be only a problem for those players who can afford to play through all those APs. At the moment, I'm "only" reading the APs because I don't have a group, but when I think of my old group we probably would have needed at least 2 years to go through a single AP so this theme wouldn't happen at the game table as often as it is in the books. So assuming that I didn't read the AP I don't run I probably wasn't even aware of this coincidence.
Apart from that, I think that Lord Snow is right on the money. Most players aren't used to "lose" anymore and tend to consider it as unfair if it happens. So it would be a real stunt to involve them in events they can't (or arent't supposed to) win for story reasons. On the other hand most AP adventures are all about stopping threats so to have one or two bad things happening in their absence serve to remind them that they simply can't be everywhere.
I understand the criticism, though. It can be hard when such a catastrophe is the reward for you following the plotline aka doing what you are supposed to do by the author. Especially if you don't even have a choice or possibilty to do something against it. Personally, what I would like to see is to have the PC make the choice between different threats. And while they stop one threat letting the other events run their course. I'm not sure though that this is doable within the frame of an AP-format adventure because you would have to use space to describe events the PCs eventually won't have a part in. And it could be equally depressive for the players to know beforehand that there will happen bad things they can't stop (If we stop the assassination attempt on the king, noone will be there to stop the orc invasion).