I'd say it's because the designers have realized high feedback voltage source design that was popular in 80's and 90's doesn't sound that good. Amp design continues to evolve. The days of low efficiency speakers combined with high powered amp is now gone. Speakers are getting more efficient and there is less demand for high powered amp today.
Why Don't We See More High Current Electronics?
It seems that in looking around for amplifiers and integrated amps that double their power as the impedance is halved (high current), they seem to be in a minority. Is it just more costly to build good-sounding high current electronics and the market demand for them just isn't there, or what?