Very good question...
And where is the cry from the MSM for DISCLOSURE of THOSE secret docs???
My theory on the billing records based on knowing Web Hubble for years is, Vince Foster discovered that Hillary was over billing the clients when preparing the trust and tax returns and this is what caused his death. Hillary has maintained she did little work on Casa Grande and that may actually be true, she just billed for non existent work. She needed and wanted the money more than Web( who married rich and had tight "good ole boy" connections to bring in business) and started the scheme.
I agree that the billing records are the key to Hillary.