Most or all of these decentralized currencies are fully centralized, which means that from one second to another the coin could crash or get hacked or something and there is no more dollar value.

Then why would they proclaim they are decentralized? What's the purpose of that?

I think it provides greater security so some people prefer it - good for marketing probably.

TrueUSD is not the same as Tether.Tether is printed constantly and not truly backed by any real value.

Well,whether tether is backed with usd is still not certain,but TrueUSD seems like a better option at the moment.

oh i thought controversy with tether is solve.