Is it a mandatory requirement to have a namespace to create Lightning components?

Hi,

Every component is part of a namespace, which is used to group related components together. If your organization has a namespace prefix set, use that namespace to access your components. Otherwise, use the default namespace to access your components.
Another component or application can reference a component by adding <myNamespace:myComponent> in its markup. For example, the helloWorld component is in the docsample namespace. Another component can reference it by adding <docsample:helloWorld /> in its markup.

Lightning components that Salesforce provides are grouped into several namespaces, such as aura, ui, and force. Components from third-party managed packages have namespaces from the providing organizations.

In your organization, you can choose to set a namespace prefix. If you do, that namespace is used for all of your Lightning components. A namespace prefix is required if you plan to offer managed packages on the AppExchange.

If you haven’t set a namespace prefix for your organization, use the default namespace c when referencing components that you’ve created.

Hope it helps.