It would be useful to be able to easily and efficiently fetch a list of the properties that are defined in a given Wikidata item via Lua - for example, so that infoboxes that fetch specific properties can be made more efficient by only fetching properties that have values.
As things stand, to get a list of the defined properties in a Wikidata item, it seems that you have to call mw.wikibase.getEntity first, and then call entity:getProperties(). This returns more information from the Wikidata item than is necessary, which increases server load.