A government would be responding to customer demand.

Sure, they could create a centralized digital currency. But the market might not want to use that, so what's even the point of spending all this effort making it in the first place.

Whereas a decentralized currency has features that sounds me customers want.

Currently, demand for cryptocurrencies seems indistinguishable from zero. At the same time, demand for government issued centralized money is quite large.

History has seen rapid changes in the demand for government issued money.

The word "rapid" on that phrase was an entirely different meaning from when it's used to describe the rate of change of cryptocoins demand.

A large market is a more stable market. Crypto may get large at some point (I don't see why they would, but I don't see everything), but today they are nothing. Thus, preaching that people massively want them is nonsense.

A cryptocurrency would be less under the control of the government, which could well be a feature.

not for the government...

But perhaps for other governments and other parties. The customers.