Necromancers are one of the most popular requested jobs, not only in FFXIV but in other MMOs as well (Wherever they're not available). However, the reason why we haven't and probably won't ever get a necromancer job is because of how they're morally viewed both in-game and irl. Among the various jobs we have, it can be said that necromancers are the most that cross the line of morality in a negative light.
A necromancer running around in town would raise alarms and spread fear among townsfolk if lore-prospective is to be taken, but thinking of it. Is it truly the case? Are necromancers necessarily evil? Black magic is considered to be a forbidden art by more than one culture, and while white magic provides beneficial effects, it's still considered less of the same (Thanks to the Padjal). We also have reapers who cross the line and directly deal with voidsents and dark knights who mostly do not give a good first impression.
Despite all the mentioned above, the WoL is capable of being all of them with no lore or moral issues, as they're not used for evil or selfish ends. Which makes me wonder if the same can be applied to necromancers?
Must the necromancer be someone who raises the dead? Or just a category that has some schools of magic under it? Ice (Frost) is an element often associated with death in many media. Would it be an issue if a school of necromancy focuses on using frost spells instead of utilizing zombie minions? Another example would be blood-themed spells, which focus on stealing the enemies lifeforce to empower your own. We already have this for DRK and RPR but it's another idea for a necromancer beyond the generic image.
I believe it's possible to pull out a necromancer job in a new concept that is different than what we already have from previous FF games, as it shouldn't be limited to one concept.