I think the idea behind TMP--especially with them thinking it was most likely a one time feature rather than the beginning of a franchise--was the chance to do things at a level that was previously impossible on a 1960's television budget. It was almost like saying, "This is what it's supposed to really look like."
While fans can be concerned with continuity and consistency the producers might not give those things the same weight. The changes seen in TMP could be better rationalized if it was set about a decade after TOS rather than only three years.
But even that doesn't explain the appearance of the Klingons. There isn't but one measly snippet of reference in the film to at least allude to the drastic change in their appearance.
If I'm not mistaken the issue was addressed by some writing the books at the time (after TMP's release) where the idea took root that what we saw in TOS and TMP were two distinct races or types of Klingons. That idea worked well enough until TSFS and TNG onward where the new model Klingons were used exclusively. TUC seemed to be the only blip in that universal depiction.
While fans can be concerned with continuity and consistency the producers might not give those things the same weight. The changes seen in TMP could be better rationalized if it was set about a decade after TOS rather than only three years.
But even that doesn't explain the appearance of the Klingons. There isn't but one measly snippet of reference in the film to at least allude to the drastic change in their appearance.
If I'm not mistaken the issue was addressed by some writing the books at the time (after TMP's release) where the idea took root that what we saw in TOS and TMP were two distinct races or types of Klingons. That idea worked well enough until TSFS and TNG onward where the new model Klingons were used exclusively. TUC seemed to be the only blip in that universal depiction.