Sure respect to each other is necessary, in the end this platform is about interaction.
Sorry but you still did not convince me and as an example you mention:
'The value of a sovereign fiat currency directly relates to the productivity and real resources of the particular sovereign’s economy, this cannot be said of Bitcoin and other crypto currencies.'
How could not Bitcoin or any other crypto currencies does not directly relate to productivity. Lets look at Mining as an example. (remember I mentioned that there are still some issues to be resolved about crypto currencies as a whole ecosystem.) Do you really think the mining activities does not relate to some sort of productivity? All the infrastructure and solutions designed to lower energy consumption. If you refer to productivity only about activities related to manufacturing, farming, etc... it is another thing, and it is just a question of time. One could not compare digital currencies which has a decade with Fiat currencies which works over centuries. Time is the answer. Look at the development towards faster CPU mining, again directly related to productivity in this ecosystem. We are still in the ecosystem adjustment phase of digital currencies.
'What has a Fiat currency failed to offer that Bitcoin and other crypto currencies can offer?'
In one word. Decentralization & Transparency. Look at the actual conditions of most sovereign states as you put it. Most sovereign states have a debt to central banks which control the Fiat system, to the privilege of few shareholders who profit gains by the interested paid from sovereign government (people tax contributions) )towards Central banks. This circle in my view killed the Fiat currency system. You are probably aware about that. It is a problem that none politician was ever able to resolve and will never will. Looking at it's aspect, your suggestion that controlling existing sovereign currencies to serve the public good as a solution is not attainable because the Fiat system itself is a system already set up to favour Central banks shareholders, only. Who are those shareholders? How much are they worth of? You see. No transparency, we are never able to look at their financial dealings, while in the digital ecosystem it is possible (although some crypto currencies like Zen Cash & Monero works to erase this transparency caracteristic but those crypto will fail with time). Cryptocurrencies cut those deficiencies right at the start. This is just one and the main characteristics that Bitcoin and crypto currencies can offer. The issue about Tax, comes to the point that we are still in the development phase, I would say and all of those things will adjust itself. To end this feedback I will forget about Bitcoin and mention another cypto currency called Ripple. Ripple payment system will change the landscape of the digital currency which will eventually affects productivity in its core. You guys, the opposition of cryptocurrencies play unfair. This is just the beginning. The market capitalization of Fiat currencies = trillions every single day, while the market capitalization of digital currencies = 200 billion. By the market capitalization itself we are able to see that digital currencies did not influence all sectors of productivity yet. I do respect your insecurities about how much digital currencies affect production as a whole, but it will, it definitely will because it is possible. Give us time because as the poet songwriter sang to us...The Times They are a Changing.