Yeah, but can't the same be said of U2's work over the last 15 years? I'm not going to listen to ATYCLB or HTDAAB all the time or as much as the albums before them, but when I'm in the mood for it, I actually like it a lot. Same with SoI. Some songs have very strong lyrics, some have strong vocals, some have strong guitar, some have strong rhythm etc. I can find something redeeming in pretty much every U2 song of the last 15 years, save for a few songs.
In the case of St. Anger, there's nothing about it that is redeeming. It is awful across the board. Lyrically, it's atrocious. Production-wise, it's terrible. Musically, it feels like Metallica changing their sound to get a radio hit (compare it to rock music of that time, you'll see what I mean) rather than doing something brave and evolving their sound.
Believe me, 15 year old me wanted to love that album, having loved Metallica's earlier albums. Couldn't do it, though, and their 2008 album wasn't much better. I've tried over the years to listen to both but every time end up hating it more than the last time.
This new album is pretty good for a hard rock record in today's musical landscape. It's far superior to its two predecessors. Not sure I'd rank it above 90s Metallica or 80s Metallica, but maybe with more listens I might change my mind.
Of course, it's just my opinion, but to call Metallica's first two 00s albums less boring than U2's first two 00s albums...not sure I can see the logic in that. I think the overall reception by fans/reviews by critics says it all. HTDAAB and ATYCLB were very well received by critics and many fans adore those albums (as evidenced by the popularity of those songs at concerts). Just about every Metallica fan I know hates St. Anger and the album was very poorly received by critics, too.