The battle royale was mostly terrible, IMO.
I really liked Peter and Harry teaming up, but I hated how Venom and Sandman were portrayed. I just hated Venom, in general. Sandman was OK, but should've never gotten THAT big, as well as just drifting off at the end like "Yeah, I'm sorry. Talk to you later, Spidey." It was just a huge letdown, just like the whole movie was.
The scenes after that were terrible. Harry's funeral should've been highly emphasized on, and not lasting 20 seconds. Also, the final dancing shyit was stupid. Also, I felt that the final swing was needed, so we could see Peter continue to progress in NYC, as well as give a final sendoff to the potential trilogy.
Spider-Man ended depressingly (in more ways that one), and it had the final swing. I see no difference in why this couldn't. Maybe it didn't have to, but with this ending which had no substance whatsoever, it definitely would've helped.