There are many reasons for this, but in fact one of the most simple is their age, in most countries there is a minimum age needed to become a Senator, which means that most of them are old, and as we know there is a generational breach that sometimes is impossible to overcome.
So while for a young person something like bitcoin is something they can easily accept, as their lives are more and more digital, this is not as easy for those of the previous generations, and as such they have problems accepting a form of money that is impossible to touch with their hands.
So lets narrow it.
1. Age
2. Things they do prefer which is on those old and not to this new era where everything is almost dealing with online or digital
3. Emotion
4. Sticking on what government do allow
5. Being not open minded
6. Doesnt accept changes or have that principle on what he should believed.
etc.
As part of governing body on a particular country then you would stick out on centralized things no matter what.
The reasons that you are giving are the most important ones, however and additional reason is that while in a truly democratic government the power will change hands, we also know that in most countries there are a series of actors that have so much power that they are the power behind the power.
Those people do not see with good eyes something like bitcoin as the control they have with fiat currencies is so extreme that anything less than that feels like a loss to them, so they are not willing to give up the power they have, and this is why they oppose bitcoin and any decentralized currency with all the influence and power they have.
