When I was a kid you couldn’t move for stories where the alien-ness of the new world was the point. Certainly the ’70s equivalent of YA fiction was full of bold human explorers meeting weird planets and weirder inhabitants, even if a lot of those denizens turned out to be really very human indeed, except that some other apparent monster was their larval stage, say, or they had a symbiotic relationship with something interesting. And if you looked hard enough you could find, say, Lem’s Solaris, which is probably still the benchmark for the truly alien in fiction.
Either the alien planet trend went out of fashion, or those books just didn’t get written as much for adults, or else I just missed out a lot, but until relatively recently I just didn’t run into books about people encountering the alien on the alien’s home turf. In the last few years, though, there has been a distinct flowering (a particularly apt phrase in one case) of books about colonising the alien world, and the compromises we might have to make to do so.