As I have posted the aircraft did indeed have a plane ready to takeoff afterwards. As a passenger in the plane about to follow, SQ6, how would you feel?
I have not dismissed the fact that an object could have caused the accident, but certainly the weather would have either played a part in that, or made the situation worse.
However, there are performance considerations to take care of. A 744, which would be relatively heavy would not have the same potential to power its way out of a windsheer incident.
Eg, on my last CBR-MEL flight, in an A320 weighing 58-60ton (very light), we had a Vr of 157kts (20+ higher than usual). Why, because of windshear considerations (I don't remember the windshear exactly, but we didn't have very large gusts). But can a 744. Unlikely, because it there isn't the runway length, and you could potentially push max tyre speed. We're talking about a very heavy plane as well (11hr sector ahead + reserves), 30kt gust components, no easy task. Windshear, etc. I'm quite sure the pilot would have taken this all into consideration, but considering all the factors, this does not leave huge margins for error. Vr is only 1.1vs. At say 160kts (my estimate Vr for this, had there been calm conditions), a 30kt gust, potentially can take you back 18.8%, back past stalling speed.
Naturally, the pilots would have increased speeds in anticipation for the windshear & gusts, but you don't have the same potential in the 747-400, you would run out of runway if you wanted to take it to the same level as the A320 situation which I mentioned. Flap 20 is a decent load of drag, especially at high speeds. You don't have the same amount of power to play with, you don't have the same margins - you're not playing with a half empty plane with plenty in reserve (passengers do not make a significant proportion of weight - relative to other things).
In this case, maybe size and weight could be a minus. Remember, the other planes (from what I've heard) are not little Cessnas & Pipers, they're relatively large jets.
I don't want to seem like I'm blaming the pilot, which I'm not, but what I'm saying is, the 744 would have less margin for error than other craft (which are quite reasonably sized, we're not talking about Cessnas.). An object could well have caused this tragedy. My knowledge is more with this type of matter - weather & speeds, where I can say something at least. I'm not a jet pilot, I'm only a amateur pilot, however I have an understanding of jet operations.
But as I've said in other posts, it could've just been very unlucky. More likely, it's a combination of factors - all terribly unlucky. If anything, I would feel for the pilot. Whether it is his fault or not, imagine the emotional rollercoast he must be going through. One can only imagine.