Folks,
Just drifted past and thought that one unresolved element was worth discussing.
That element is the tendency of PPRuNe discussions to cross the world without adequate recognition that each jurisdiction has subtle differences in both its rule sets and their application.
There is a previous discusion herein on the application by the FAA of despatch vs inflight landing distance factors, as well as identification of the significant differences that apply in Oz. Some of our newer readers need to note the limitations inherent in our discussions, lest they misapply some other country's rule in their own backyard.
Having noted that, a crucial bit of the original discussion is to identify the difference between certification requirements and operational requirements.
The certification requirements are all "flat earth" rules to ensure that the bluddy thing will fly with a modicum of ease. Approach climb limits ensure that there is some OEI climb capability at the other end and and the landing climb is there to stop the manufacturer from achieving the world's shortest landing distance by using flaps that render the aeroplane incapable of going around.
The operational limits are simply how we attempt to meld those "flat earth" capabilities into an environment full of lumps and bumps. We do a lot of planning for take-off and generally nothing for landing - one significant reason is an absence of agreed data on the geography of a missed approach. Think about the complexity of trying to work out the distance from the decision point to achieving a stable climb after reconfiguring for go-around from an ILS, runway-aligned NPA or a circling approach. Do the planning templates in TERPS or PANS-OPS really reflect real life?
Best of luck...