I would submit that A) Avasculate is consistent with evil witch legends (Stygian Witches, Baba Yaga, Iggwilv, Hag types, etc.) and B) that particular Necro-sadism chain may have been left off as an oversight or could improve the class by adding,
Are you arguing for X-warren (et. al class coder) that A) Avasculate is dissimilar to the Witch theme / spell list or B) Coder spell choice cannot be improved upon or suggestions made to?
Since 3rd party stuff is not official, the PRC coder (i.e. the one doing all the work / adding value) has the final call. I personally recommend going with the spirit of things, especially on judgment calls.
For those interested in benchmarking the 3.5 spell list, here is a good resource:
http://www.greenronin.com/errata/grr1302_3.5_update.pdfProt from Spells, Trap the Soul (drool - Lich Soul gem like-spell - drool) and probably a few more.
3rd party stuff is good to keep coming, but can be improved upon.