Jumbo Driver.
Your point has merit for checklists that we are familiar with and use on every flight, namely the Normal Checklists.
In this case however we are talking about a Non-Normal Checklist. Admittedly the "One Engine Inoperative landing" checklist has deferred items ("Approach", and "Landing") which are very similar to the normal landing checklist, however there are many many non-normal checklist that we are not familiar with. Hence the reason why the PNF reads out the challenge and response when running through Non-Normal checklist.
I suppose to be consistent, ALL non-normal checklists must have PNF/PM read the challenge AND response including the One Engine Inoperative Landing checklist.