I wasn't aware Strange New Worlds was bringing back this look:
While the armor the Klingons wore in the Motion Picture did pretty much become the standard garb for all Klingons the makeup has hardly remained unchanged.
Heck, Worf's look changed pretty much season to season:
Attachment 132178
People are certainly free not to like the latest Klingon design, or even to believe that there was no reason to mess with it further...but to say that it wasn't continually changed overtime whether it was to fit the budgets of the particular show or movie or aesthetics of the creators on a project just seems objectively wrong to me.
For me personally, I'm mostly fine with simply accepting that make up changes over time and have never needed an in universe explanation. That said, though I never had a problem with the changes I do like the avenue that was opened up by Enterprise with the augment virus and I feel like that if you did want an in universe explanation you could piggy back off that and say the Discovery look was an attempt at Klingon's using genetic engineering to bring themselves back to their roots and that the more alien look we saw in Disovery was them going too far back and so they continued to tinker with it. And then in TOS what we see is a faction of Klingons who didn't go in for the gene tampering gaining control, hence the lack of ridges.
Is it complicated? Yeah, which is why I'm for accepting the reality of the situation, but I do think an entertaining story could be made of it if they wanted to explain it in universe.