Our team uses the email to requestor feature, but we find that Wrike is missing a key feature that many other request systems have – which is sending automated emails to a requestor based on the status their request is in. Example: When we "complete" their request, they will get an email noting "your request has been completed." Many comments in this thread are asking for this feature as well.
Adding every single requestor as a collaborator is not an option for us to consider at this time.