I think a big part of the problem is attitude.
People like Clarke, Mills etc. seem to treat everything as a chore - and charging the fees they do, and constantly jetting around the world etc. they can be forgiven to a certain extent. It does get silly though.
That said - not so long ago Jeff Mills was paid a very large sum of money to come up and play here in Notts, with his new DVD-J set etc. The contract had no manner of silly little things into it: Jeff must recieve 1000 Euros - in 50s - upon arrival... Chauffeur-driven Mercedes from Heathrow, no music - no talking... etc.
In the end, for whatever reason, he didn't play with the DVD-J's. When the crew responsible tried to rig up some cameras etc. so that they had something to project on the screens, Jeff's manager said "no cameras on Jeff"... To top it off, many people I know said that the night was remarkable only in it's mediocrity.
IMHO the root of the problem is this. When the likes of Mills, Clarke, Sims etc. were becoming big names, competition in the DJ world wasn't so fierce. Play some good tunes, mix with 3 decks occasionally, knock out some decent 12"s every now and then and people will love you.
The fact is that talented DJs are ten a penny these days. You show me one Jeff Mills and I'll point you in the direction of at least 10 equally (if not more) talented DJs - many of whom are registered on this forum, and wouldn't dream of trying to charge what Mills does.
Not at all trying to knock any of the past masters - just point out that it's a different ball game these days, and you have to do a hell of a lot more to get noticed. For more info, see: Jerome Hill, DJ Bam Bam and Pet Duo.