While there are many advantages of forming and implementing policy at the federal level, including protection of minority rights, uniformity of national regulatory standards, and increasing trade and job mobility, there are some issues which do need to be handled on the local or state level.
First, economic, social, and environmental conditions vary from state to state. Issues concerning water rights and usage in the arid southwest are quite different from those in the humid southeast. Racial and economic issues are complicated by the legacy of slavery in the former confederacy, while in many western and southwestern states, Native, Hispanic, and Asian American populations are more significant minorities. States such as Kansas and Iowa need policies to cope with rural depopulation, while many east and west coast cities need to address rising inequality and housing and other resource shortages due to an influx of immigrants from other states and countries. No one set of environmental or economic policies can address these varied issues.
Although having a single bureaucracy, instead of multiple, handle policy can simplify paperwork, it also eliminates checks and balances and can lead to overly close and even corrupt relationships between the bureaucracy and the industries the bureaucracy claims to regulate. Having multiple agencies involved serves as an important set of checks and balances against complacency and corruption.