back in 1e, reincarnation was a 6th level wizard spell of the necromancy school. material components were cheap (a drop of blood and a small drum), and they had to have died fairly recently. it was also a 7th level druid spell, but the druid spell would restore you as an animal most of the time, while the wizard version always left you as a humanoid.
2e removed the spell from the wizard list entirely. 3e gave druids the old list from the 1e wizard version. and now pathfinder has given wizards limited healing ability with the conjuration school.
so why not bring reincarnation back for necromancers? there is precedent for it in the rules, and its not a balance issue as druids now get it as a 4th level spell. wizards still have clone, so this would simply be a faster way for them to revive the dead with side effects.
