Given that the quotes API already returns each data field as an array containing one value, it appears as though the intention has always been to expand the API to support returning data about multiple equities in a single call. However, I do not see any open feature requests for such functionality, so I am opening this request.

Supporting multiple equities per API call will reduce load, both on the server side and on the client side. Additionally, hosted client apps may impose request limits or rate limits that can easily be violated when making one Market Data API call per symbol. Batched requests would reduce the impact of such limits.

Note, this feature request may be similar to "Multiple option symbols in a single request," but this one is concerning the stocks endpoint.