Wow, killing off the love interest to give a more important character motivation, that's not a bad cliche at all!
Also, what do you mean Josuke didn't have a personal feud with Kira!? What about Shigechi!? Josuke was actually buds with him for a bit, while he was still kind of skeptical of Yukako! Also, trying to merge the Atom Heart Father fight into Bites The Dust (Which doesn't even make sense, since the first time they fight Yoshihiro is way before that part.) would make things unbelievably hectic and messy. (And not in a good, weird Jojo-way, just like, "this battle has too many different components for anyone to be able to think of a good plan against it.)

(cont)
Lastly, while Rohan could easily GTA an ambulance with Heaven's Door, I think that actually doesn't do his feud with Kira justice at all. Because Rohan isn't an actual fighter, his Stand doesn't do direct damage, it just allows him to make other people do his dirty work. And that's what Rohan does in relation to the search for Kira, he's not out there ready to fight him, he's looking through pictures and reading people's minds, trying to gain clues, at which point he can call in Jotaro and Koichi (And begrudgingly Josuke and Okuyasu…) to come kick his ass. Also, Rohan isn't the only person who lost someone to Kira? He didn't even remember it had happened at first. To me, a random citizen of Morioh killing Kira is the perfect ending, since Kira isn't really any one person's enemy, he's the enemy of the whole city, a plague upon it. Being killed by such a direct apparatus of it feels right, to me.
This anon's desire to settle all these "feuds" with largely unneccesary physical violence betrays the Part 4 essence, that it's not always about big muscles beating people up and who can be "the strongest", it's about what's inside people's heart, hence why Josuke is so nice and the villains aren't super-dangerous assassins and vampires but largely normal citizens being jerks with their powers.