My impression is that much more is going on than is stated explicitly in the e-mails. Things don't usually percolate in big organizations for nearly 2 years without someone pushing it.
Harriet Miers doesn't seem to me to be a person who would be pushing these things - she strikes me as someone who does what she's asked. Who asked? Well, who stood to benefit from the changes? Friends of Karl, perhaps? People worried about losing the House and Senate in close races, perhaps?
IOW, the need to follow the trail wherever it leads. Don't, at this point, accept that it was Miers and Samson's fault because they were freelancing (or something).
Cheers,
Scott.