There is a service parameter that can be configured in the service settings:

Signup requires a description of intended use
Developers requesting access to your API will be asked about the purpose of their API.

(see screenshot)

This settings claims that when enabled, the developers will be asked about the purpose of the API on signup, however, in fact this setting doesn't seem to be affecting any templates on the developer portal.

NOTE: This checkbox is visible ONLY when "Multiple Applications" feature is Hidden – which is confusing itself.

Solution:
Remove this checkbox and any differences between the view for when "Multiple Applications" feature is hidden and when "Multiple Applications" feature is not hidden. (The checkbox does nothing anyway).