Have the writers forgotten about Celestail Warlocks?

[Witty Username]

It seams like the writers wrote the discription and mechanics of the Celestail Warlock in chapter 1 of Xanathar's and then forgot about them.
There seams to be very few Warlock spells particularly higher level ones that do not seem thematically inappropraite for a
Celestial Warlock.

I have never heard of a Celestail warlock.

I think it is more indicative of the problem of trying to define differences between themes with a short list of spells. It seems like their thought is that you only need 10 thematically appropriate spells.

Likewise, a spell such as Sickening Radiance can be reskined into Awesome Radiance....many Earth mythologies incorporate the idea that unfiltered Divine Power destroys material matter.

Isn't material matter just matter?

Reskinning can get you places, also warlock has a lot of theme neutral spells like hypnotic pattern, banishment, dimension door etc.