95% of the movie-going public is not going to have any idea that the shot was recycled from TUC. And, as was observed above, a Bird of Prey exploding is not going to look that much different no matter how many different times you film it. If recycling a few shots from TUC enables them to save money and create better effects for things like the crashing of the saucer section, I'm all for it since that, and not the BoP explosion, was really the signature action moment and effects shot of the film.
All of the criticisms of the story, the ability of the BoP to defeat the Enterprise, and so forth are valid. But the re-use of previous effects shots is not the problem.
(And, BTW, if the Duras sisters have gained access to the technical information visible through Geordi's VISOR, I think they could
have made it realistic for the BoP to defeat the Enterprise. I mean, they could penetrate the Enterprise's shields, thereby neutralizing it's primary defense. However, I think they should have added a line or two of dialog explaining that the first shot or two damaged the weapons systems. Thus, as in the battle with Khan in TWOK, the Enterprise is left with the ability to fire one or two shots at most, and have to make those count. Then it becomes plausible they hold their fire until Data implements his shield-dropping trick.)