The copy of 1984 you show as an example was published in 1954, so if we take that as a point of comparison then are you trying to say that Richard Powers was painting garish pulp covers?  That's absurd!  If you are referring to the 30s and 40s, you may be right to conclude that the imagery of BEMs, rayguns, and Earle Bergey amazons with metal brassieres became the MEME of Science Fiction cover art, for better or worse.  But please don't trash the work of Edd Cartier, Virgil Finlay, Hannes Bok, etc with your imagined lurid trash.  You're only contributing to the popular perception of art that was fostered by Science Fiction pulps and paperbacks as trash, when in fact it included some of the more fantastic and talented illustrators of the 20th Century!   Should Time magazine have dumped Boris Artzybasheff in favor of Wall Street Journal style hedcuts?  I don't think so!  Nor shoud anyone lament the wildly creative art of the SF pulps and paperbacks.