Quoted from CaptainNeo:
you will learn that theme doesn't matter. People get so caught up on theme, and miss some awesome games, or are stuck with a lot of shitty games. Some of the best themed games are horrible horrible games. And some with themes nobody gives a crap about, are phenomenal! It all comes out to layout and rules. How they work together. That is the key factor. hence why it's so risky to buy a game you have never seen or played in person.
Of course theme matters. Here is proof: here is a very, very fun pinball game. The theme is The Kardashians. Will you play? I rest my case.