I’d say it’s more than just aesthetic. AFAIK, most other apps that support YAML also add it at the top so it might help with keeping it compatible with most other apps.
As someone who also uses a lot of DataView inline fields, there’s still a distinction I often make to decide which field to use where. As a general rule, any YAML fields apply to the entire note itself like it’s creation/updation date, type, source, etc. And any Dataview fields I use often only apply to the current line/section I use it in. As an example, I use #Watched:: and #Read:: quite a lot in my daily notes. Each of them is in a bullet point since watching or reading something is just that one point of the day and doesn’t really reflect my entire day so it doesn’t need to be in a YAML field.