A common workaround after Twitter attempted to kill third party client apps was to have users register their own "app" and insert the API keys. So this will put a stop to that.
You only require approval from twitter and a product website if you have higher usage than that, which is what would prevent you from using that workaround.
> Beginning today, anyone who wants access to Twitter’s APIs should apply for a developer account using the new developer portal at developer.twitter.com.
Existing API keyholders:
> Eventually, all developers with existing access to our APIs will be required to complete a developer account application in order to maintain their apps.