Actually the quality of things like amplifiers has gone downhill, high end Hifi had superb quality handpicked components and the power amplifiers were meaty affairs - now everything is built down to a price with rubbish Chinese components - the facilities are vastly better but component quality has gone backwards and cheap powered subwoofers can make a system sound good to an untrained (more accurately clueless) ear, most people these days wouldn't know good sound if it smacked 'em in the face, they listen to music compressed into MP3 or AAC though a "HiFi" designed to accentuate bass and treble - stuff detail or the accuracy of the sound stage. As for things getting better the system in my 99-2000 Rangie isn't even vaguely as good as the (OE upgrade) Harmon Kardon system I had in an old straight 6 XJR back in 1995. The stereos in my two subsequent V8 XJRs weren't as good either - louder and bassier but sound quality was poor - they couldn't handle loud transients - sign of a weak output stage and underspecced capacitors. But then nothing in a car can be called HiFi the fact it's in a car will always compromise sound.
The output stages in my HiFi power amps at home weigh about 5Kg each with enough copper to keep a pikey happy for a month - but then each one is worth more than my Range Rover so I'd expect them to be good quality. British HiFi is still the best in the world.