I think that a lot of what your pointing towards stopped after it all kicked off in 1990. I don't think the simple fact of Jay-Z representing 'bling' culture particularly represents any kind of the end of an era, cos the end of the era was probably 1990 imo. I went along a few times after that and still enjoyed a couple of them but it was clearly taking a much more commercially hard-nosed approach when fences were erected, the travellers field stopped and specialised bastard security bought it to intimidate the punters.
Rod Stewart, Paul McCartney, David Bowie, these have all played in recent years so i wonder how they fitted into your feelings of what Glastonbury stands for?