But the Companion, Medusans, and the TOS Tholians were expensive, because they were optical effects. They also suffer from not being able to physically interact with other characters in a scene. Even Melvin Belli's horrible Gorgan character was an optical, forcing him to be motionless and possibly not even on the set when talking to Kirk.But more non-humanoid aliens would be a welcome sight. I can't believe it's a technical or budgetary issue. Aliens like The Companion, the Providers, Sylvia and Korob, the Medusans... not humanoid, not expensive, very alien.
Oh sure, the Tholian. The Horta, the Melkot, Yarnek. I can see those being costly. Nomad, too.
But... the Providers were rubber brains with a light bulb (with voiceover). Can't be more than the cost of a guest actor to play an alien. Same with Sylvia and Korob.
The Companion was an optical effect, like the Zetarians. Not to belittle the effects work, but flashing lights and some animation is effective.
The Medusan was a light in a box, with some flashing overlays. Couldn't be too expensive.
More costly than a guest actor with makeup work?