I grow all almost all of my neps outside of terrariums. Most are on wire racks under fluorescent lights, some are in windowsills. I never mist them, but here in San Francisco we have pretty good humidity. Almost always over 50%. I have N. aristolochioides, N. mira, N. lowii, and many others all pitchering happily. The only ones I have in terrariums are N. x trichocarpa, N. albomarginata, and N. ampullaria, and I'm sure they'd all do fine outside the terrarium, too.
If you have decent enough humidity naturally, no terrarium is needed.
Capslock