Most of the bands you guys have listed haven't really been forgotten, but that's just my opinion. I'm a diehard. I'll list some bands that made some great records during the 70's but were never really known enough in the first place to be forgotten all these years later.
See how many you guys recognize:
Sir Lord Baltimore
Budgie
Dust
Captain Beyond
Night Sun
Cactus
Bloodrock
Toad
Lucifer's Friend
Point Blank
Three Man Army
Trapeze
Randy Holden
West, Bruce And Laing
Hard Stuff
Stray
Jeronimo
Hawkwind
Flower Travellin' Band
Some of those are pretty obscure, no doubt, but all of them released albums that are definitely worth checking out for anyone interested in 70's rock.