Thor is an alien with tech indistinguishable from magic. Green Arrow is a highly skilled crime fighter that uses tech. Guardians of the Galaxy are superheroes in space.
Trek spent almost 30 straight years on TV. It needed a rest.
Space Sci-Fi in general is more expensive to produce and thus needs higher rates to draw in expensive advertising to support those costs. It has nothing to do with "too much this" or "too much that". Quality, entertaining stories and good production win through.