• They recognise the consequences of too much power for big business;
• but do they understand what they would replace it with? 
• Would greater power for nations and states help the world's poor?
• Why does the world never make up its mind as to whether State power or business power is best (or worst) for humanity?
• Is there any hope?

First where the protestors are wrong
We know that they are against the globalisation of trade and the free market. (That is they are against the utilitarian and individualistic philosophies of global capitalism.)

But what are they for? 
Do they believe that each nation should return to a state run economy and by the force of law reduce its trade with other nations? It seems so. Yet it was state controlled economies (so-called collectivist economies) in the 20th Century that were responsible for more human suffering than all the suffering caused by all other tyrannies in all history put together. (The sheer numbers of the state killings - even excluding victims of war - confirms this.) 
The G8 leaders were right to say that wealth creation comes from free trade. (Every time a genuinely free exchange of goods/money/services takes place the wealth of both parties is increased. Therefore any restriction of this free trade - by state power and law, monopoly power, or corruption - increases overall poverty). 
It follows that best way to help the poor is to maximise the potential for free trade and thus globalisation should be encouraged.

Second in what ways were they right?
They were right to show that monopoly power in the hands of big business inevitably leads to exploitation. It is evident all over the world. (There is too trade in harmful products such as pornography and druges - the State has a responsibility to prohibit such trade).
So they believe the state should have a role in curbing the power of multi-national companies. 

Right, but how is the power of the state to kept in check? By the electorate? Yes but what influences our thinking. The media? Yes but how is that enormous power to influence and even control our thinking kept in check?

Our human tendency for self-corruption can only be kept in check if we know that there really is a purpose for human life and that purpose does not have its origin in our own desires. 

Here is a profound comment from a former British Lord Chancellor (The emphasis below is added.)
Lord Hailsham writes:

It is, I believe, for this reason that any attempt by the politician to drive religion out of his philosophy has always led to one thing, which is man's almost total inhumanity to man.  In the end the utilitarian and individualistic philosophies of the nineteenth century led to the 'wail of intolerable serfdom' spoken of in Disraeli' novels.  I need not say to what the collectivist philosophies of the twentieth century have led.  ...   It is a belief in man as a creature made in God's image, to use the poetic language of the Old Testament, which forms the protection of man from the extremities of indifference or oppression.   It is the objective validity of morality as proclaimed by the sages of all nations which explains and justifies the perpetual tension, the endless dialogue, between individuals and minorities on the one hand and the State on the other, between freedom and authority, between liberty and law.  In other words it is the free will and the rationality of the individual, the dignity of the individual, in  tension with moral responsibility of the individual which explains and justifies the writings of the political authors, the debates in Parliament, the regulations made by Ministers, the treaties concluded between sovereign communities, the demand for freedom, and the necessity for law which constitute the history of the West, and ultimately of all mankind.  The fact that these things are not measurable, calculable, or verifiable explains much, perhaps all, of the argument. But the fact that they remain objective realities proves that the argument is not about nothing.