Case is a special entity in CRM because it has many out-of-the-box special logic. Sometimes this can be problematic as it forces us to use some fields we might not need.
I’ve always found many customer scenarios in which the “Customer” field adds no value to the case and we would like to remove it. Although less often, you might have found a scenario in which the “Title” field of the case is also not needed. The bad news is that CRM forces you to use those 2 fields in the case, otherwise you might encounter some issues.
For the “Customer” field you can get around it but you need a plugin which is going to set your customer to a dummy hard-coded customer on the Pre-Validate operation whenever a case is created. I haven’t seen this work with sync workflows or business rules (although I haven’t investigated much), unfortunately seems like a plugin might be required for this. Once you have this plugin you can simply hide the Customer field from the form, make it read only and remove this field from all the views. Then your Customer field will be used but not really used. Note that in order to hide this field from the form you might want to make it read-only and then move it to a new "section and hide the entire section. This will help you keep things clean on your form by moving all the “unused” but “locked” fields in a hidden form section.
Regarding the title field, CRM will not prevent you from not using this field. You can also hide it an make it read-only and things will seem to work fine. However, as soon as you start using SLA’s you will run into this problem:
Workflow '{F5245D54-9BA6-4E4B-AB86-9131A076FB4D}' failed due to error: Unhandled Exception: System.Collections.Generic.KeyNotFoundException: The given key was not present in the dictionary.
at System.Activities.WorkflowApplication.Invoke(Activity activity, IDictionary`2 inputs, WorkflowInstanceExtensionManager extensions, TimeSpan timeout)
at System.Activities.WorkflowInvoker.Invoke(Activity workflow, IDictionary`2 inputs, TimeSpan timeout, WorkflowInstanceExtensionManager extensions)
at Microsoft.Crm.Workflow.SynchronousRuntime.SynchronousWorkflowActivityHost.ExecuteWorkflowUsingInvoker(Activity workflow, ICommonWorkflowContext context)
at Microsoft.Crm.Workflow.SynchronousRuntime.SynchronousWorkflowActivityHost.StartWorkflow(WorkflowActivationData activationData, ICommonWorkflowContext context)
As you might know, SLA works as workflows behind the scenes. As soon as you create SLA’s there are some background processes (workflows) created which represent the SLA you have created. Some of these workflows are synchronous and it turns out that if your case has no title, the workflow fails with the above error message preventing the creation of the case. This can be easily fixed by either using the case title or placing some dummy value in it. In our case we simply copied the ticket number into the case title. However, one must admit that it is difficult to arrive to such conclusion from the error message above, that is why I’m sharing this finding, I hope you find it useful!