"One-armed bandits" have come a long way since the days of lining up cherries, and today's slot machines are multi-media experiences that often tie in with current entertainment trends, including blockbuster movies and popular TV shows.
And there's part of the answer to your question: What's hot today is often forgotten tomorrow and the race in Hollywood to come up with the next big thing is mimicked by those other affiliated products piggybacking on a brand's marketability. While you may still be enamored of the Star Trek game, others have evidently moved on, because if the machine was still raking in the cash, it would still be out there on the casino floor. It's a ruthless slot-eat-slot world out there and only the winners survive.
One of the problems with games that feature an existing brand, be it a TV show, movie, board game, or even a celebrity, is that someone else owns the rights to that brand, which have to be licensed from the copyright holder(s), and that's invariably a complicated and expensive proposition. Developing a new slot game is already a painstaking process involving lots of stages, and if you add a costly third-party license into the mix, a game has to really kick butt to make it worthwhile. And, even if it does, the brand owner may change their mind down the line and decide that they don't like its association with a casino game, or they get greedy and want to up the fee, and hence a license may not be renewed even if a game is proving to be popular.
While themed slots can all look very distinctive, in reality the bells and whistles can be easily adapted -- it's generally just a matter of switching out some glass panels and replacing the software that's generating the graphics and sounds. So, even though the slot game you miss may be gone from the casino floor, you may actually be playing the same physical machine, since the hardware tends to have a much longer shelf life than the gimmicky game that plays on it.
