Conlanging isn't just gibberish, it's a legitimate artform like anything else.

However, I don't have any issue with using real-world languages to give the desired exotic flair for certain settings. I actually think that was one of the things that was great about, for example, the Avatar: The Last Airbender cartoon, because it took the time to use real Chinese calligraphy as part of the worldbuilding (one of the many flaws with the film adaptation was that it tried to deemphasize the explicitly Chinese influences and ended up with pretty uninspired chicken-scratch fake-ideograms for the writing).

Similarly, the video game Riven: The Sequel to Myst had some cutscenes where the fantasy native population were actually speaking Tok Pisin, which is a creole language from Papua New Guinea. This was only fragmentary, though, and much of the Myst games have a quite well constructed language "D'ni."