It would be helpful to users of web map apps, created using the AGOL templates, to have the layer list reflect the scale-dependent list of layers in the legend. Currently, the user has the option to toggle layers in the layer list that may or may not be displayed at that scale, which is confusing. Another approach is to put an optional toggle right in the legend.
I have a regional county polygon layer for small scales with one symbology and another county layer for large scales with different symbology, both called "Counties", but the user does not know which to toggle because both layers are listed at all scales.
This idea would help in my (& user's) transition from classic layer-based paper cartography to modern multi-scale, multi-layer, dynamic, web-based applications.