The MEP usually do not "rubber-stamp with barely any changes". There often is considerable change applied to the original proposals, by the MEP negotiating. What really is missing is the right to propose laws for the EP. But for that you would need to agree about a way tighter EU integration of the member countries, which currently seems highly unlikely in the given political climate.
Again, it is way easier organizing a democratic system in a single nation state than in a confederation of sovereign countries with sometimes very different national systems and views. And I am not saying that to brush over the democratic deficit of the current EU implementation, but just to acknowledge the level of difficulty.