Not only would I say that it is almost wholly due to them that U2's shows are so successful, I would say that due to their work there are an infinite number of bands that are able to sell tickets because of them.
As almost every big live show has now taken video content on as a major aspect to the performance, this can be directly attributed back to Zoo TV and Popmart. Other bands like Pink Floyd (also a Fisher/Park client) always had video content, but the LED work with SACO, Williams, and Fisher on Popmart clearly re-defined the live show. Any band that tours an LED screen today can thank those guys for their success, and there are few bands that can sell out large rooms without them.
They revolutionized the big live show and I do not think a band could sell out a stadium today without the work they have done.
In terms of the creative aspect - they get involved very early on (as I was told by Fisher in his flat in 1996) as the music is being recorded (or in 360's case, even before) and the band basically approves or rejects the creative ideas. So the whole 'dreaming up' aspect for the musical direction is the band, but almost everything else about the live show has come from Williams / Fisher and formerly Jonathan Park.
I stand by this - and pose the question, if the band was playing on a plain jane rectangular stage with no wizardry, with this last record, do you think they would sell out stadiums?
I, regretfully, do not think so.
Axver - please elaborate.
I am with you in that the JT tour was phenomenal, and that era of music is very much my favorite. But if the band did not have this creative team behind them, what do you think we would be seeing today - assuming they would still be touring today...