No, it wasn't. It was propagated by someone which caused the following response on the Common Issues and Recommendations thread "Using an interface (usually called IHasModel) on your Item and/or Block classes to denote that they are capable of registering a model is an anti-pattern and not necessary. All items require a model to be registered for them and usually no type-specific information from the item is needed, only the registry name, which is accessible for all items by default."
As for the issue above, that's just how minecraft constructs their quads for generated item models if I'm not mistaken. If you would like to 'fix' the issue, then use a model creator (e.g. Blockbench) to create the model yourself and use that as the parent.