I see your complaint, as I would prefer more jedi and light sabers too. But for the time this movie is set in there are no jedi for Vader to fight, so it is what it is. And Jynn vs Vader in a duel?
That's a 3 second fight where he wouldn't even need to break out the saber to kill her. I was expecting him to come through and just wipe out the entire cast of the movie at the end, but I'm not mad a the more fair and honorable death direction they chose to go
For me Star Wars without jedi/sith/the force is definitely inferior to Star Trek, but this movie had enough of a connection to jedi & sith for me to enjoy. But I have no interest in that Han Solo movie though.
There's no reason to have any Vader on the big screen anymore either since the prequel to og bridge has been completlely finished... Having him hunt down and kill nameless jedi or go on excursions with Sidious can just be left to the comics and books