In my guesstimation, many of these shows *may* have been coded for VG2, making them small and not of high enough quality for VGHD. Couple this with low ratings, a lack of interest from the community and other, newer models being filmed, it's likely she was dropped from the schedule...
I understand that with new technology and time a number of shows are being reprocessed for the new format. We can only hope her shows are counted among this number...;)