Perhaps because all of the abnormal indications on this paticular flight related to the number 4 engine only and it was that one that finally threw it's toys out...
Do all those abnormal indications in the cockpit give you a
complete overview of the situation? How can you be certain that there is not more to it? Let's look back a couple of months: Did the EK 777 crew (
flight 132) have an indication of the outside physical damage? The indications available on the flight deck do not necessarily reveal the entire situation. Continuing a flight because everything seems normal, does not mean that it is safe.
I fail to see your logic. Three is still better than two - at least in my eyes when I'm crossing several thousand miles of ocean or mountain-chain!
Flying on one engine isn't a big deal either! Or with partial landing gear. Just ask the crew of HL-3378. The authorities were so impressed by the captain's decision that they revoked his license (shortly before his retirement).
Airmanship. Where do you draw the line between operational need (better: pressure) and safety? One could also argue because a certain item is MEL'd that it is (still) safe.
Where's the attention to detail?