In short, yes.
But it's an inevitability, if a rock band goes on for a long time.
I'm sure on Rolling Stones' boards, there are plenty of threads about "Did the Stones to irreparable damage to their legacy by carrying on after 1972" (akin to U2 post-Zooropa), and "Did the Stones do irreparable damage to their legacy by carrying on after 1982 (aking to U2 post-Atomic Bomb). And I'm sure there are lots of fans who say, 'No! The Stones did lots of classic songs I can't live without in those eras". But to the casual music fans, or to the casual Stones' fan, the answers is a resounding YES.
So it is with U2.
For me, personally, I think their classic / essential / legendary period of unbridled creativity and vitality ended with the recording of Zooropa. Yet, I was mostly on board with their mostly fine releases from 1997 to 2004, as well.
Definitely, since 2005 or so, I've not really enjoyed U2 in sum anymore. The odd tune grabs my attention, but the amount of mediocrity -- largely, it seems, as a result of their obsessively chasing cultural bigness over quality music -- is disappointing, and two of the last three albums were crappy. I suppose a lot of casual U2-fans jumped ship then, as well, and since 2009 have lost interest.
So, it's a toss-up: If U2 had ended in 1994, we'd be able to look back on an all-killer-no-filler career of young guys in their prime, like The Beatles or whatever. But on the other hand, if they'd ended then, we wouldn't have 'Please' or 'Beautiful Day' or 'Every Breaking Wave' or 'The Little Things That Give You Away', etc.
The unanswerable rock'n'roll question has always been: Is it better to burn out than to fade away?