So on the Rubin argument- everyone is entitled to their opinion but calling him talentless or overrated is a bit crazy. The guy basically reinvented rap production for a pop audience and also modernized the recording style for hard rock from "echo chamber tap chords with effects and pedals" to a more range - oriented structure focused on vocals and simplicity. His work with the Peppers in the 90s and System of a Down later speaks to this, as does his work with Cash. License to Ill was revolutionary for its era and people who overlook that probably forget what other contemporary artists sounded like in that genre.
What is also true is that rumors of how direct (or indirect) a hand Rubin plays with his artists in the studio, particularly in more recent years, have only increased. He has had a series of trusted engineers he works with and the rep is that they routinely do 75% of the work while he occasionally Skypes in to add thoughts before taking lead in mastering and sequencing. He also lets the artists bang the songs and shapes out before he adds his touch at the later period. For a band like Green Day or the Peppers, who have a well developed style of songwriting/instrumentation and bring song ideas to the studio, that makes sense. For a band like U2, who prefer to improvise and change course often during their early sketches for an album, it sounds like a completely incompatible match. Rubin is about as far away as you can get from Eno and Lanois, who at many phases of U2's recording life were the 5th and 6th members of the band, at least in the studio.
I have gripes with all U2 producers (mostly Lillywhite) but it's clear that at least personality-wise, Eno and Lanois were their best match. The body of work shows that, and same would be true of Rubin and many of his artists. Scott Litt was a perfect fit for REM. Hugh Padgham could tolerate 3 colossal egos with the Police and made classics. Managing personalities is perhaps more of a mark of many effective producers than some realize. My hope is they find someone, like Barlow, who can channel their creativity again as well.