Redundant administration? By that logic, you might as well create a one world government, but it's a piss poor idea.
Consider that redundancy is good in that it creates multiple points of failure. Consider that bureaucracy will scale with the size of the country and not necessarily in the efficient way you think it would. Consider that regional needs and cultures vary dramatically. Even in individual countries, subsidiarian governance is good in that it best matches law and policy with the particularities of each region because local authorities have better grasp of local issues (and where matters are escalated only as necessary). Blanket statements about bigger being better are flatly wrong. And where the US is concerned, the US benefits greatly from a very fortuitous combination of geopolitical factors. Russia, on the other hand, expanded eastward with no such commensurate benefits.
Consider that redundancy is good in that it creates multiple points of failure. Consider that bureaucracy will scale with the size of the country and not necessarily in the efficient way you think it would. Consider that regional needs and cultures vary dramatically. Even in individual countries, subsidiarian governance is good in that it best matches law and policy with the particularities of each region because local authorities have better grasp of local issues (and where matters are escalated only as necessary). Blanket statements about bigger being better are flatly wrong. And where the US is concerned, the US benefits greatly from a very fortuitous combination of geopolitical factors. Russia, on the other hand, expanded eastward with no such commensurate benefits.