LOL...ATYCLB, despite being more mainstream than what they'd done in the 90's, was more socially adventurous and textured than anything on the current record. Not to mention that it had some absolutely amazing songs and at least one U2 classic.
I don't agree that ATYCLB had "absolutely amazing songs". Not to any noteworthy degree. Elevation is utter tripe. Stuck is schmaltz and Walk On has proven to be U2 on autopilot. Now...Kite is worthy of any song they've done in the back half of their career. When I Look is a nice 'Side Two' gem but nothing more. And if Beautiful Day were on SOI, it would be...Every Breaking Wave. The primary difference being one song was greeted by a mass audience eager to fall in love with U2 again and the other was greeted by a mass audience that just wants them to go away. Either way, both are the same type of thing, done pretty well. Only...arguably...Every Breaking Wave is a lot less cliche in content. Whereas BD reads like a mix of motivational poster slogans.
So Kite...BD...what else? A few other nice tracks, I suppose but overall, that album gets more love out of nostalgia and the zeitgeist of its cultural moment than the actual musical product. Completely unremarkable, top to bottom. SOI is clearly a better album just based on songcraft, but that's still not saying a hell of a lot. I don't know what is more "socially adventurous" because I don't know exactly what you mean by that. But I will say that musically, creatively, they were at least attempting to wander into some new territory for them...as well-worn territory it was for almost anyone else. I give them that credit where it's due. I've always rejected the notion it was a 'return to the 80's', it absolutely wasn't. No, that's SOI.
Speaking of these two albums, in my view, ATYCLB and SOI share the most DNA in their "aim to please" formulaic and safe nature. The biggest difference being that SOI has better songy material (I'm trying to save myself a lot of descriptive words and wanky self-indulgent "I'm a musician" talk) and ATYCLB being more original, but not by a lot. SOI, for as much as it succeeds in what it aims to do, is the most derivative thing they've ever done, creatively.
And maybe the most innovative (for U2's own sound) song on the album, to me, is one of the most explicitly pop/desperate for a modern "hit" songs they've ever done - California. It's a good song, I like it, but it sums up SOI quite nicely. Really well done, catchy, unremarkable, inoffensive, easily digestible, formulaic. It could have fit on ATYCLB in that it wasn't really new to anyone in the conversation but U2 themselves. And only mildly at that.
It's like ATYCLB's better looking (sounding) cousin, SOI, in that sense but neither one of them is going to occupy much space in the chapter of the Book of Great Rock n Roll that discusses what made U2 remarkable.
IMO, over these last many years (17 by current count) U2 have done their best to be as unremarkable as possible in order to be as popular as possible.