Pure speculation, and so not relevant to this conversation, but I feel like Angus is one of those guys that, in his living room, can bang out the entire Mussgorsky Pictures At An Exhibition piece on acoustic guitar. Or maybe I'd just like to think that.
I think - for me anyway - as much as I love AC/DC, their singular focus has not gained them credibility, but lost them a little credibility. People change. People grow. People evolve. Someone like Ritchie Blackmore - who is way off the reservation compared to his work with Deep Purple - to me has followed his muse. Even Eddie VH; Van Halen today doesn't sound like Van Halen from 1978. Other than my taste in women ("I get older, they seem to stay the same age") there is very little I like now at 50 to the same degree I liked it when I was 20. Even Iron Maiden went prog, then dropped an acoustic song into the mix. By staying so singular in their approach, it sort of smacks of calculation and "product".