Power usage is actually going down significantly at large events as tungsten sources (outside of theatre where we really need the spectrum and useful colour temperature shift) die off to be replaced by either discharge or LED.
The sting in the tail with discharge is that because they do not usually hot strike well the lamps tended to stay lit for the whole gig, neither LED not Tungsten has this issue.
Sound power is never a particularly interesting size of load, mostly because average power is so very much lower then peak power, but you try telling a noise boy that yes, that 50kW rig really will do just fine on that notionally 10kW feed (it will, but no way the sound guy will believe you).
There was pretty much a step change in speaker performance about 10 years or so back, efficiencies went way up, and pattern control improved massively, a modern PA box is in the well north of 105dB/W @ 1M, so you can make a LOT of noise with not very much amp, and some modern speaker hangs approximate a cylindrical wavefront in the near field, so only fall off at 3dB per doubling instead of 6dB.
Sound these days tends to follow the 'get it digital as quickly as possible' school of thought, you just don't see cables the size of my arm carrying 64 individually screened pairs any more, instead you just scatter a few MADI (Or these days, Dante or AES67/Ravenna) boxes around the stage and run a coax, fibre or cat 5 out to the desk. Not very rock and roll maybe, but a couple of 1U network switches and a Gig-E over SFP and fibre link is smaller, lighter and very much cheaper then humping great flightcases of arm thick cable with delicate 160 pin ends.
Modern amps sometimes do not even have an analogue input any more, instead sitting directly on a data network, and in fact integrating such things into powered speakers is not uncommon, you just wind up running ethernet to a switch mounted on the flying hardware and running power and data to each box.
It changes the system engineers job somewhat and sometimes wireshark and knowing how to use a fusion splicer is more important then knowing how to solder!
Time was a synced pair of 500kVA machines was fairly standard at these things, these days you might run a pair of 250kVA machines and load shed a bit if you lost one of them.
Agreed that LED can be a curse, mainly from my perspective because all the power supplies leak small amounts of earth current that adds up and can take out a RCD even while you are still well within total current limits.
Regards, Dan.