Ok, if that's where we're going
I respectfully disagree. It was a great opportunity to ease the continuity issues caused by bizarrely making them suddenly devils in 4e, but they tried a middle option.
That conjuring wizardess was the girl your take out on Saturday. The cute elven archer in the "Dragonslayers" piece by Elmore was the girl next door you take home to meet mom.
Back on topic - where are you getting the information on the new Succubus/Incubus (and Eyrines).

The 4e ecology informed the 5e MM. That ecology strived to bring the succubus/incubus closer to its roots in mythology and folklore while reconciling the conflict in its demon/devil background in D&D (very challenging).
I had the opportunity to do the 4e incubus (Demonomicon) and 4e succubus ecology (Dragon Magazine), so when the succubus/incubus ended up among my assigned monsters for the 5e MM, I was pleased. I was more pleased when the main points the story team and D&D community wanted from the succubus/incubus more or less aligned with that work. Big thanks to the community for choosing those details and bringing the succubus/incubus home to its real world mythology.

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.