I can't remember if Zack addressed this in one of his many interviews now... But one fan theory has it that he's getting back in touch with his Kryptonian roots, so it's more a matter of identity. Like he feels the need to ground himself in his Kryptonian identity first before he can wear the blue and red again.
Remember, in MoS Jor El, Zod, Faora, et al., all wear black suits. In MOS Kal's dream sequence with Zod (or actually, I think Zod is talking to him while he's still delirious from adjusting to the Kryptonian atmosphere) has him in the same type of black suit Zod is wearing.
I hope that we get some backstory on the meaning of the blue and red in contrast with the black suit. I don't care if it's original to this story. Like does it have some special meaning? Does it signify some sort of distinguished status or achievement for the House of El? Etc.
Anyway, after Superman succumbs to the anti-life maybe he will feel he's entitled to wear the blue and red again except for twisted reasons, as a kind of evil god on earth.