The main reason why businesses and large corporate companies have not accepted Bitcoin, has to do with government regulations. A business cannot accept Bitcoin as "legal tender"... if their local government has not approved it.

So, this is the barrier that are placed by governments to protect their local currencies. The reason why they are protecting their local currencies are simple, because they have full control over it. (How much is printed... who owns it.... how much they own... how they spend it... etc..)