To be fair, there's a school of thought amongst classical musicians that you should perform without having the music in front of you if you're a solo performer or doing a concerto, not so much if you're sitting in a full orchestra. Anecdotal evidence, sure, but when I was in college working on my piano degree, it was very much frowned upon to perform at a recital or other concert with the music in front of you because it indicated you hadn't fully memorized the piece, and from that point you can master the music without worrying about forgetting notes. In Jordan's case I think his parts are way more complicated than a vocalist carrying one melodic line, but I bet Jordan can play all those songs in his sleep anyway, so I dunno.
But that's very different from Halford's position, I don't think it's bad per se, but more than anything I'm just curious why he'd need one after decades of singing in the band.
@Stads: I get the same impression, I understand what you're saying. One of the reasons I want to see Maiden live is that electric 'have fun and enjoy some fucking metal' energy they exude, especially Bruce.