Siri requires Location Services for certain questions

What question are you asking?

You can ask Siri what is 2+2 and the answer will be provided without location. Asking what the weather is in Athens will require Location Services to be turned on. You may not think it needs your location to answer that, but Siri wants it and you have the choice to turn on Location Services for that answer to be provided or not.

None of us work for Apple and "why" questions are unanswerable by us because we are not given the inner workings of Siri processing when Location Services will be required. I have found any question related to map data will require it to be turned on, whether it needs to know your location or not.

In the previous weather example with Location Services turned on, if you are in Georgia you will get the weather in Athens Georgia and if you are in the UK you would get the weather in Athens Greece. Even if you ask for the weather in Athens Greece, since it involves map data, Siri will go no further without Location Services turned on.

Asking a city-state question is Map Data and like previously said that is going to initiate the Location Services request.

There is no additional information from Apple.

You can send feedback to Apple directly here. It is mostly a one-way communication for feature requests and bug reports, so don't expect to get a follow up:

Feedback - iPhone - Apple

Using Siri is a personal choice and not a requirement. If you prefer to use a different personal assistant, there are many to choose from.