I like Oasis alot, but to me, ever since Be Here Now, they've been treading water.
I think the main problem has always been their reluctance to change, people get bored so quickly these days, always looking for the new and leaving behind the old and I think at some point the industry just moved on without them. I think they've slipped beneath the radar.
I think the casual listener feels that if you've heard one Oasis song, you've heard them all, and they'd be justified in thinking that, Shock Of The Lightning is a decent track, but it sounds like exactly the kind of thing Oasis has done many times before.
Bono was smart in realising that after Rattle and Hum, U2 needed to re-think the whole outfit, new sound, new image, whole new approach, it was the only way to remain relevant and creatively inspired. This is what Oasis should have done after Be Here Now, I think it would have given the band a fresh shot in the arm and potentially made them even bigger, but that's just not Liam and Noel, the idea of changing or experimenting seems to make them uncomfortable.
I also agree with Vlad that UF, JT, AB, Zooropa, Pop are all great records.