I have to take exception to a few of the more general comments you make.
- Campy: Star Trek was not campy. Look at the old Adam West Batman
series for an example of campiness.
- Silly: Again, I do not feel that 'silly' is the word you are looking for. Compare with Lost in Space
for an example of silliness.
- Low Budget: Trek
was among the highest budgeted show of its time. Some episodes, typically ones that took place entirely on board the ship, were done to make up for budget over runs on other episodes.
Many of the actors, including Shatner, were stage trained and experienced. This led to some of the affects that might be called 'over acting.'
Like any show, it is a product of its times. It is unfair to criticize special effects as being poor when they were typical of the day, especially for a TV show.
I will allow that some episodes could be termed 'silly' or have some aspects that were silly - Shore Leave
and A Piece of the Action
to name a couple. Episodic TV could, and still does to an extent, include some episodes that differ in tone from the bulk of the series. This can be attributed to different writers or to wanting to introduce some variety to the show or just to actually have some fun. Star Trek
was noted for its use of humor and humor produced some excellent episodes, such as The Trouble with Tribbles
. It was also successfully employed in STIV - The Voyage Home
(although fans differ on whether this was a 'good' use of humor or not).