Florian Fricke of Popol Vuh got rid of his synths after only two albums, so the answer is clearly “1972”
That actually sounds very reasonable. We probably were In Love With The Future for only half a century or so, from the dawn of commercial aviation, popular motoring, electrification, radio and telephony, as celebrated by the Futurist movement, through nuclear fission to the jetliner, space exploration, television and plastic wonderstuffs, as seen in Liechtenstein et al.
We now return you to the present day.