Toriyama complained about Goku's characterization in Toei filler even back in the 90s. It's nothing about being senile. It's not just the dub, filler was already messing up his personality even in Japan.http://www.kanzenshuu.com/translations/wired-japan-1997-akira-toriyama-interview/>Wired: There’s actually “poison” inside?>Toriyama: Right. There’s how, basically, Son Goku from Dragon Ball doesn’t fight for the sake of others, but because he wants to fight against strong guys. So once Dragon Ball got animated, at any rate, I’ve always been dissatisfied with the “righteous hero”-type portrayal they gave him. I guess I couldn’t quite get them to grasp the elements of “poison” that slip in and out of sight among the shadows.
Now, Dragonball Super's characterization of Goku has its own problems too though. It's pretty clear that Toei's writers can't buy into Goku fighting just for fighting's sake in spite of not being allowed to make hims super heroic... so, we pretty much are getting nothing character-wise from him. For example, they remove him being disappointed he needed the ritual to face Beerus in BoGs, but then add nothing to replace that.
Everytime they need him to surpass his limits, they go back to the whole "friends! family!" pool too, but they obviously they can't do it much either since it'd clash with Toriyama's directive, so we end up with a half-assed characterization that doesn't sell him as heroic, but also does very little interesting with his love for fighting and martial arts.
Toei's current writers inability to see love for martial arts as a primary motivation is why Tenshinhan ended up shafted so much too. They clearly just don't know how to handle that considering how even Goku suffers from it, so with a secondary characters they just sidelined him, something they obviously can't do with the protagonist.