Despite Dark Pit having a different Final Smash compared to Pit, his Final Smash is still a cloned move, just not from the same character all other moves are cloned from.
I think characters are better defined not by their moves but by their identity and characterization. If Dark Pit had the Three Sacred Treasures somehow, but still retained his personality and character traits, Sakurai coming with whatever explanation for why he uses the 3ST, I'd be okay with it.
It bothers me more that the localization team butchered Lucina's personality in certain lines than Ganondorf being a semi-clone of Captain Falcon. Lucina acting smug to Marth and Ike is out of character for her and is something that doesn't happen in the Japanese version, where she's in awe to have fought against such legendary characters in flesh.
Knowing that she's correctly portrayed in the Japanese version alleviated my feelings regarding this. The rest of her English lines are overall okay, except her "You'll never defeat me!", where the tone is a little too condescending: if she had a similar tone to her "You will not stop me!" critical quote from FEA, it would've been more in-character. Her personality is also intact in the trailer, so it's really a few lines that were poorly done.