Blame Cotugno and her SJW activism.
Nefcy was certainly Californian, progressive liberal, but the early instances of this found in the show were far more digestible, moderate, and there was at least some care to showing the gray nature of the themes that were presented, even if there was an obvious bias. Nefcy and Dominic were perfectly capable of progressing the interesting aspects you've outlined, particularly after the love and effort put into the Spell book to make some of those aspects shine through.
Instead, they gave the young upstarts and chance to gain some XP, and in the process, they fucking trampled over that well manicured garden throughout S3 and S4.
With any luck, it may serve as a warning to any other future creators... Don't trust your rabid, activist subordinates with the IP you've poured your blood, sweat, heart, and soul into. They don't deserve carte blanche rights to reshape it any way they see fit. They won't treat it with the respect or care it deserves. Keep them on a tight leash, or watch your creation go up in flames with only ashes left to show for it. But it's likely the lesson will go unlearnt... Or worse, the ones responsible for this travesty are now set loose and free to fuck up more shows.