I used to buy the answer that I wasn't looking hard enough, but now I know better. I can think of a couple bands that are trying a little change here or a little change there but I haven't found any band doing something as different as the gulf between Judas Priest and Metallica in '83 ya know? Or between Metallica and Morbid Angel. The gap between Artificial Brain and the great mass of derivative DM just ain't all that big at the end of the day. But in general a lot of what passes as innovative in metal these days are really just minor tweaks: take some generic modern DM, throw in a keyboard and a few seconds of clean vocals and call yourself Symphonic Tech Death or whatever. It's nonsense. Lazy nonsense.
I think it's a false equivalency you're drawing between catchy and saccharine (Babymetal being more sugar than Issues). Some catchy stuff is sugary sweet and some isn't. But more importantly I think bands like Issues and Babymetal prove a fundamental metal assumption wrong. Metal and sugar can mix and they can mix well. Saccharine pop hooks sound good over punchy, tight and heavy metal backing. I'm not saying that all of metal should drop everything it's doing and blindly follow, no. But I am saying that, for better or for worse, they're the only genuinely new thing to happen in metal since like '03. Is it daring to mix metal and pop? I don't care. It sounds good.