Khan 2.0 wrote:
...The idea being that it had really looked like that all along but the budget hadn't been there to show it clearly before.
yes like the klingons in TMP (Im sure the general opinion from everyone was they were supposed to have looked that way all along.... until Enterprise)
Or rather, until DS9: "Trials and Tribble-ations" showed the 24th-century characters in the same room with TOS-style Klingons and asking Worf about the change. ENT just picked up on that in-joke and built a story out of it.
And it wasn't everyone's opinion before then, not by a long shot. It was what Roddenberry suggested was the case about the TMP Klingons, and the shows were agnostic on the issue until the reuse of TOS footage in "Trials" forced them to acknowledge it. But in fandom and tie-ins, there were a ton of theories about the different types of Klingons. John M. Ford's novel The Final Reflection
posited that Klingons often created genetic fusions with other species, and that TOS Klingons were actually Klingon-human fusions. DC's graphic novel Debt of Honor
acknowledged the existence of two races of Klingon without explaining why they were different. Michael Jan Friedman's My Brother's Keeper
novel trilogy showed Klingons in the early 2260s genetically engineering a new, fiercer variant of themselves which was implicitly the TMP-onward style of Klingon (though I don't think Paramount allowed him to make it explicit). A Howard Weinstein storyline in DC's ST comics had the crew going back in time into Klingon history, and showed smooth and ridged Klingons coexisting even centuries in the past.