Hi,
Hikashop supports joomla 3. This is important for people who can't upgrade their joomla. Also, for people wanting to upgrade, being able to have their Hikashop up to date before migrating the data base tables makes for a smoother migration.
And joomla 3 does not support web assets.
Also, it is false to say that all the HikaShop scripts are always loaded on all the pages.
First, you have a setting in the HikaShop user synchronization plugin to load HikaShop or not on all the pages. Loading HikaShop on all the pages allows users to be able to use the HikaShop content tags on any page of their website. But if you don't need that, you can turn this option off.
Also, not all the scripts are loaded. HikaShop only load the scripts it needs based on how you configuré each of its éléments. For exemple, the media/com_hikashop/js/checkout.js file is only loaded during the checkout.
Similarly, HikaShop only loads jquery when one of the options you're using in HikaShop require it. We've tried really hard to dépend on it as little as possible and only a handful of capabilities require it.
Now, if you don't want HikaShop to load any JavaScript file anywhere, there is a hidden setting you can activate for this. However, in that case, it will bé up to you to load the JavaScript necessary for the capabilities of hikashop you're using ( for exemple by adding the JavaScript in the template ). But I don't recommend doing this as you'll struggle with updates in the future.