Subject: Do we really understand the resting membrane potential?

Why, if macroscopic electroneutrality is not violated by cells, we do measure a 
voltage difference between cell's interior and extracellular milieu? Is it all 
due to infinitesimal differences all long the cytoplasmic membrane, acting as a 
capacitor (possessing a charging capacity inversely proportional its thickness)?
Electrogenic pumps provide part of the answer, but the total cancelation of ion 
fluxes in steady-state seems quite arbitrary (but one need this assumption to 
derive equations such as Goldman-Hodgking-Katz). 

Re: Do we really understand the resting membrane potential?