I'd be curious to see if there were production memos between the TUC producers and the TNG producers about just what could be modified and what couldn't; the modifications done to the various TNG standing sets all seem like things that could be easily redressed back to their TNG appearance. Revamping the warp core like you suggest might have been too involved, and so they were stuck doing the best they could with a warp core that was clearly an anachronism.On the whole, I would agree. I think, however, the warp core would have looked better using the later-rebuilt Voyager configuration, that used a similar intermix effect that the TMP refit had. That TNG core, with the animated red and blue neon light hoop blinkies always looked really super-cheap to me.