Why has the eleventh amendment been hotly debated in the legal system?

The Eleventh Amendment  basically states that the federal courts would not listen to cases in which one state is sued by another state or a foreign state or even by the citizens of the said state. This is done in order to ensure the balance between the sovereignty  of the individual states and that of sovereignty of the federal government. The debate is held because there is no clear agreement whether this strengthens or weakens equality.