I only watch DBS because I loved the old series. To be honest, I don't think many people would stick to it if it wasn't Dragon Ball, not would they be so complacent, because the new series has so many flaws it's not even funny.
In regards to the plot, I actually like the Black Goku arc a lot. My problem with that arc is some very odd or illogical things. For example, Trunks shrinking back to his early Android saga look, The Mai-Trunks pairing which came out of nowhere (it's cute, but it doesn't make any sense how they got together in 2 timelines), the ending which was utterly terrible. Trunks' Rage form also made absolutely no sense and I hate how just getting angry gives you God level power, and the Potara retcon was really bad (Why not just use the Potara over and over again now? It used to have a decent limit).
As a whole though, the arc felt like good fanservice combined with a new appraoch. Future Trunks came back like we wanted, Goku became a villain (sorta), Fusion was used by an enemy, and the villain was rather smart and planning for once. Scenes like Black Goku killing Goku's family were absolutely chilling.
In terms of the characters, yeah they felt off from the start. Goku was always goofy, but he was intelligent as well. In this series, he's an absolute moron and is causing the destruction of entire universes. Vegeta used to be prideful, sometimes arrogantly so, and this held him back in some ways but empowered him in others. Now he really does feel like Goku's sidekick and the "always 1 step behind" thing is exaggerated, and he was so quick to act wimpy in many situations.
The current arc is showing a lot more terrible trends. Apparently Super Saiyan is a cakewalk now, with new characters with no experience whatsoever achieving Super Saiyan/Super Saiyan 2 and beyond with ease, one of those characters kicked Super Saiyan Blue Goku's ass with ease.