My explanation would be that the 1,43 factor (requirement to land within 60% of LDA) is because in planning phase you only take the forecasted weather conditions into account. And even if forecasted weather turns out to be more optimistic than the actual weather, you will probably still end up with some margin in the landing distance.
It is also to prevent cowboys from scheduling a flight into (too) short fields. If you take off, you have to land somewhere, but scheduling a flight with minimal (15% or even lower) margin to LDA would be very stupid.