The continued touring/deification of older, "canon" artists has destroyed innovation in guitar music, and it will take generations to properly recover, if at all.
Think you like metal? You start off and listen to the classics like Metallica, Maiden, etc. and you can still go and see them, so why bother trying out new stuff, especially if it's just a variation on the core themes (honestly when was the last major sound shift in metal - nu metal 20 years ago?). Let's be honest, if a 3 day metal fest like Download decided to limit their headliners to bands that only got big this century the'd be fucked after a year or two.
Trad UK guitar indie has died a death, so moderately good bands (Idles for example - good, but by no means amazing) get hyped up more than they should be. All that's left is nostalgia gigs for those my age, so they can take their kids and pretend they're still cool.
I honestly don't know if there is anything new that a guitar band can possibly do now; all the reference bands are so well known now that everything is kind of a pastiche of an older, probably better original. Guitar music has lost it's ability to shock, and their isn't any point of difference between what the new generation and my generation listened to for me to get upset about it not sounding the same as what I grew up with.