Hi,
Note that this thread is 3 years old. 2 years ago we released HikaShop 3.0.0 which came with a brand new checkout system.
In the HikaShop configuration, under the "advanced" tab, you have the "checkout legacy" setting you can activate to go back to the old checkout.
Supposing that you're doing that, and that you do the modifications in components/com_hikashop/controllers/checkout_legacy.php instead of components/com_hikashop/controllers/checkout.php, you might be able to have it working.
However, with the new checkout system, doing this would require completely different modifications.
If you're a developer and want to look at that, you'll want to edit the file "show_block_address" via the menu Display>Views to skip the display of the address area when needed. And you would have to modify the file administrator/components/com_hikashop/helpers/checkout/address.php to validate the address step even without any address entered when needed.