The two features that are desperately needed in Simple Store are:
1) The ability to specify different shipping costs for different products instead of a blanket global shipping cost for all products.
2) The ability to specify sales tax for different USA states and not a blanket tax for all states. I only need to charge sales tax in California but Simple Store applies it to all purchases.
These two features are desperately needed ASAP for our new web store otherwise we'd have to look for another web builder that has these basic eCommerce store features. Of course we'd prefer to stay with Strikingly long term as we already built a site so we hope these two features can be implemented as soon as possible!