Such over-rated scenarios are neither challenging nor fun. The job of the author is to pick that level. And to keep the scenario balanced so that a required encounter that is hard for the party isn't followed by encounters which are trivially easy for any party which got through the earlier one.
Many players have by now a full stable of parties of various levels and equipment.
The level you set is displayed in the scenario pick list of BoE when the player is choosing what scenario to play. It provides a guide to the player so that he can select which of the available parties will yield the most fun in this scenario. Let's see this room. Hack hack hack. Your goal as an author is to give the player some fun, so you need to pick a suggested level that will be good for the average player.