Why are custom fields not supported in Consul services?

I found a few circumstances where storing metadata for adding specific services would be handy, however custom fields don't seem to be supported in the services API (Basic ID, Name, Address, Port only). For example, the name of the database or the weighting of the load balancing.

I am curious as to the design decision - is there a best practice that this evangelizes or perhaps is this future improvement that can be done?

I understand that we could use the KV store for more information, but it seems more convenient to bundle such information together rather than making multiple Consul requests.