The story has been determined by fan demand and editors since early on. So this complaining about fanservice is bizarre to me. I see it everywhere so I'm not addressing anyone in particular.
DB was doing badly, so editors suggested tournament arcs. Vegeta was kept prominent because he turned out to be popular. All the different Cell forms and androids are all a result of editorial meddling. Goku came back because fans like him and Toriyama thought Gohan didn't fit the main character role.
I mean it's entirely possible to think the fanservice is badly done, sure, understandable, but I feel like a lot of those "fanservice" choices improved the story and most of the time made sense. I thought Kaioken, Freeza and 17 were some of the best additions, for example.
I don't think any of this is anything to freak out about, especially since Broly and Gogeta are essentially blank slates. If it all comes together to a good whole, who cares? Of course, it's entirely possible the movie will suck, but using popular stuff by itself isn't bad. Personally I'm also kinda tired of Vegetto and I'm happy we got Kefla in the ToP and now potentially Gogeta in the movie. All the elements here is stuff that has room for expansion and doing something interesting with them.
I think a potential attempt giving some depth to these hyper popular things is actually a good thing, too. Would be nice.
Anyway, I ended up watching movie 9 and 12 because those are some of the ones I'm curious about and I remember seeing bits from.
I liked Bojack because of others besides Goku getting to do stuff. The tournament at the start was pretty cool and Gohan saving the day was cool, too.
I loved Fusion Reborn because it did the Buu arc right, by which I mean switching between lighthearted and intimidating perfectly. It's such a fun movie because the characters are so expressive and the villain, while not having a personality has a incredibly cool moveset and personality in terms of presentation. The setting is really unique and cool-looking, too.
I love Goku in the movie because he's such a perfectly balanced wacky and fun and serious. I liked Paikuhan in there, too. In a general sense, it's one of the best-looking DB things I've seen, too. If the new Broly is as good or supposedly better-looking, then that's gonna be great. The addition of Hitler in there is some wierd and awkward stuff, but for the most part it was really entertaining.