This is simply a matter of taste. I'm a pretty hard core AC/DC fan, and have been since about '81. I can tell you IMMEDIATELY a song that came from the High Voltage sessions and the Fly On The Wall sessions. IMMEDIATELY. The production IS different. The playing between Mark Evan and Cliff Williams, or Phil Rudd and Simon Wright IS different. No, you're not going to get a concept album on the perils and pitfalls of single-payer healthcare, but, like Kiss, the vibe and ethos is just different.
If it's not your thing, so be it, it's not your thing. I listen to Radiohead and every song is drony whining, with an off-hand bash at America or whoever our President is at the time for good measure. Drivel. Worse, BORING drivel. But I know full well, if I dug in, if I cared, if I wanted to understand the nuances, they are there. I think it's a cheap shot at AC/DC to assume that "it's the same song over and over for 50 years".
Me? I'm fired up to hear Phil, Angus, Brian and Cliff back together again. Assuming Phil can tour with them, I will go see that immediately (bring your earplugs, though).