UX on user side - Suggestion
The user experience with SIA should be similar to any other cloud drive service today. Perhaps a separate user only client wallet that behaves like any cloud service app. When asked for payment, it converts fiat to SC automatically behind the scenes. That way if the user don't know anything about crypto, they don't have to. The user won't even know they using blockchain tech. Similar to the STEEM social network. Perhaps work with an exchange or credit services for the payment part.
Perhaps this can be an evolutionary step to becoming more mainstream. Anyway, this is just a suggestion. If this was not on your plans for the future, maybe you should consider implementing something similar and keep in mind the perspective of a non-technical user that knows nothing about crypto or how it works. Promoting simplicity of use could be the key for mass adoption on the client side.
@midnine - I'm not SIA, but if you look at the road map there are obstacles to overcome before the team wants to focus on the issues you bring up, which I also agree to is vital to bring it to a wider audience.
I beleive the core functionality for SIA is to become the back bone of decentralized storage and then to a certain degree rely on 3rd parties to deploy the end user functinality - they are at the moment promoting a bounty scheme where devs can win money when brining the desired functionality to live.
I am aware of the roadmap and I agree that further development is needed. This is just a suggestion for future consideration.