[PapsEdisa]

I presume you mean more in terms of instrumentals in popular music rather than say classical music.

I personally love intrstumental music, I can think of thousands of pioneering records, Brian Eno has done a couple of albums one I have called Music for Airports which is jsut beautiful, and although it must be over 30 years old now it doesn't sound dated at all.
Whereas for some reason when I listen to say, Tubular Bells, it sounds dated, still a good album nonetheless.
The key is to use sounds, techniques and instruments that are not "new", but to make them sound new.
Why Pink Floyd stuff still sounds fresh and innovative today is because they limited using "Space age" instruments, for the most part they were a rock band - Vocals, Guitar, Bass, Keyboards and drums. That sound will never sound dated.
Some electronic gizmo that whirrs and beeps and chimes may sound futuristic now, but in 30 years time it will sound like a dial-up modem.

Of course there have been some fantastic guitar orientated experimental instrumental records, Santana's "Caravan Serai" is for the most part instrumental, and probably his best album.
Paul Kossoff (from the band Free... All right now? Anyone?) released a solo album called Back Street Crawler, it's about 40 minutes long and only 5 tracks, and 3 of them are instrumentals, and the guitar playing is phenomenal, vocals would have ruined it for sure - that strat was singing better than any person could have.

Acoustic artists have long been advocates of instrumental pieces, Classical Gas for example by Mason Williams. But also Bert Jansch, Nick Drake, Davy Graham (who I saw live not a few months ago and he blew me away) Jackson C. Frank all dabbled in instrumental pieces, just the one guitar generally. And that stretches back to the days of the blues players, those we heard of and those we haven't.