First of all 99% of people who is going to answer here is wrong and the last 1% will have a message 99% wrong as well. Mostly because they got too big of an opinion regarding themselves and bitcoin as well as a gripe against the government.
Ill try give you a few actual reasons but remember that a currency is very complicated and there are allot of pros and cons however you manage it.
In no particular order:
They can not print more money. Most countries use their power to print money to balance the economy. Countries that have adopted the Euro also suffers from these problems but its not an absolute bad thing. Just a different way things are handled that requires a country to find new methods.
Its not bound to an Identity so the government can't keep track of your money and hence can't tax you on it. Especially dangerous in combination with criminal groups or terrorists like Al Qaida.
Its an experiment and not designed to be sustainable in the future or distant future.
99% right? Well you posted a few incorrect statements in your post, first of all Countries don't just "print more money" actually printing money is down to IMF, what are the IMF?
"The IMF promotes international monetary cooperation and exchange rate stability, facilitates the balanced growth of international trade, and provides resources to help members in balance of payments difficulties or to assist with poverty"
Infact, countries are in debt because of this very reason, so I don't know what you mean about countries printing more money off to stabilise the economy.
Every time a country prints more money off, the more the value of that certain currency goes down, why do you think people are sticking with Bitcoin, because there's a limit to how much there will EVER be, meaning it should get extremely value at some point. (Although this may never happen)
Now, what you said is that countries use their 'power' in order to "print money off to balance the economy", no not really, like I said earlier in this post, the countries are not the ones who actually are in 'control' therefore can't just use their 'power'.
But, back to the post.
In my personal opinion, I think they don't like it because they can't track you down, think of it.
Most ways to pay online require a bank account, a bank account needs you to provide identity.
However, with Bitcoin you don't need any of this, Bitcoin can be generated in a few seconds and sent anonymous across the web for ANY service/product.
This causes a lot of problems, for instance many Bitcoin users are branded for purchasing illegal drugs online and can't be traced afterwards.
Now, for this very reason Bitcoin as hit the news many times, it's a scare tactic more than anything.