Currently, Attachments must be a direct child of BasePart.
This puts an unreasonable amount of constraint on the instance, preventing portability and organization patterns.
Attachments have been expanded in behavior to support ParticleEmitters, PointLights, BillboardGuis and much more. But they still cannot be organized at all. Foldering or Grouping or Nesting otherwise is not allowed. This is severely limiting because it prevents otherwise clean and future proof design patterns that enable more dynamic and object-oriented systems.
For example usecase, a Platform which features Folders of associated Attachments that are turned into arguments at runtime.
If Roblox allowed Attachments to be parented anywhere, and only display if bearing a FirstAncestor which contains property Position, the Attachment object would be a correctly universal instance, among the utility of BaseParts.
PS: Where CollectionService, Attributes, are undesirable.