It's a different style or fashion of writing, as Cati says. Each country, each historical period, has its own style, sometimes more than one. Compare, say, Villon to Dumas to Huysmans to Dantec. Except for writing in French, you'd never find their styles similar. Or in English, say, Chaucer, Milton, Defoe, Wilkie Collins and Michael Moorcock.
Back when Lovecraft was writing, he was right at the end of a period when flowery language and adjective-heavy writing was just how it was done. A reader of the time would find his prose actually quite sparse; some contemporary commenters found his work numinous and scary precisely because he hinted and suggested rather than detailing the intricate corrugations of each tentacle! I rather like the style, done well, but my tastes are fairly broad because I've read a lot across the work of a number of eras, and struggled through a lot of books in their original languages.
And Rollo is correct about the style being discouraged in American English because of the politics, since that style was popular among Russian novelists. Whereas in British literature, it was edged out on the wave of post WW2 depression, anger and kitchen-sink 'realism'.
