As the title says: Why is e.g. 靴を脱いだとしたら、家に入り下さい considered unnatural and 靴を脱ぎ終えたら、家に入り下さい is the more natural way of communicating “Please enter the home after you have finished taking off your shoes”
If all V[過去形]としたら are unnatural usage — what is the deeper grammtical reason for it being unnatural?
By typo I meant the missing お in 入り下さい and not that 脱ぎ終えたら should not be the answer to the question. But thanks for your comprehensive explanation. That としたら marks hypothetical use only was exactly the bit of information that I was missing to understanding this. I thought that this had something to do with としたら being preceeded by a verb in past form.