I do feel that there are few reasons why the Pre-Order via Samsung Online Store is getting delayed
1) DHL took longer time to process the order.
2) Not enough ready stock to fulfill the Pre-Order due to MCO
I suspected that most of the stocks was delivered to Partners or Telco like Courts, SenHeng, SenQ which they delivered earlier that actual date.
Perhaps the demand for the direct order via Samsung Online Store is more than their partners thus the stocks not enought to furfill.
I noticed something on the arrangement of delivery from Samsung Online Store.
For those who pre-order earlier was delivered by DHL eCommerce, and those who Pre-Order later was delivered by Pickupp.
Those who click on the url in the order page provided by Samsung probably have seen this screen .

Probably those delivery were screwed up by DHL, thus Samsung SDS swapped to another Courier (Pickupp) instead.
Just my assumption and from what i read and see here and from the experience of my friend who did pre-order with Samsung Online Store.
I have a feeling Samsung official store ships directly from another country thats why its slow...whereas SenQ, Maxis etc they ship from that country early beforehand.