I agree with you overall, but take issue with the part I highlighted above in your post.
One could state that a song like "Elevation" and possibly "Vertigo" were more fun, rock/pop songs that were just meant to be hits. Nothing wrong with that - I could argue the same for "Mysterious Ways", "Even Better Than...", and "Discotheque" (and perhaps a few more). Just like these songs, "Elevation" and "Vertigo" have several interpretations, but no incredibly deep meaning. All songs were instantly catchy with a wonderful hook. And for that reason, there's a bit of a "throw-away" aspect to them, which I guess you equate with "killing any joy or emotion". And that's unfortunate, because sometimes when I hear a fun rock/pop song from the past, it brings up numerous fond memories of that era. And the song just makes me happy - it's light-heartedness is part of the reason why.
Still, if you want to dismiss those songs, so be it.
I would argue, though, about others. "Walk On", "Sometimes...", "Stuck...", "Beautiful Day", COBL, "Love & Peace", "Fast Cars", "Kite" - all of these songs were far more powerful and written with hints of past U2, as well as exploratory U2 (especially "Love & Peace" and "Fast Cars", both of which sounded like nothing U2 had done before and both of which could have even fit on NLOTH). There's a reason many of those songs won Grammies - because they stand out as far more than just a throw-away pop hit. "Beautiful Day" will be a crowd please for years (and, I believe, so will "Vertigo" and "Elevation").
So while it was U2's goal to make "albums full of singles" with their last two efforts, it doesn't mean the songs are bad or dismissive. The Beatles made a career out of singles and their songs still have a powerful impact, over 45 years after their release!
As for NLOTH, clearly this is not an album full of singles. "Magnificent" has that potential to be a bit hit, but it needs editing and it needs massive promotion (because as brilliant as it is, I just don't see radio playing U2 unless they really have to do so - apparently tons of hit songs, awards, sold out tours, and top selling albums means little for today's radio
). So NLOTH may indeed be the album that U2 fans will enjoy, but few else. It's a shame, but this should counter that "joyless" aspect you unfortunately felt about the last two efforts.