I think mostly it was a case of the right band, at the right time, on the right stage. But from a personal point of view...
As soon as the line up had come out i was torn between Blur and Prodigy, I'd loved both in the 90s without being a super fan of either. My girlfriend (now wife) was dead set on The Prodigy, so a fairly easy compromise for me. It was her first festival and she'd found it pretty hard going and once we'd made it round to the Other Stage from wherever we'd been previously, she declared she was spent and would watch from the tent (we were camped in Oxlyers), and was happy for me to go in and get involved. The fact that I'd had a couple of months resigning myself to missing Blur meant there was only one option, so preceeded to leg it round to the pyramid. I can vividly remember going past JP as The Wombats were playing Moving to New York!
I got there just in time and the set just built and built, soundtracking so much of my teens and twenties. The crowd, to a person, seemed so into it and the singalong during and after Tender was a moment that will stay with me as long as I live. It felt so tangible at the time, how much the crowd and band were connecting, and that it was a 'special' gig. In the weeks after the gig I'd almost convinced myself that I'd just been getting carried away, but seeing the footage of Damon breaking down on stage and hearing the band talk about it confirmed it wasn't just me.
Everything about it was just perfect.