Suffers from no government having a stake in it. If it causes them problems, it can easily become illegal.
Lots of countries outlaw other country's currencies. This is nothing unique to Bitcoin when we are talking about a world currency to replace dollars.
Several countries do now have a stake in Bitcoin. See: https://bitbo.io/treasuries/countries/
Precisely this makes it attractive. If it can't be _your_ currency let it at least be a currency no other nation controls.