Totally agree. For me you either have something new that's hard to explain in "one sentence" or you do a remix(because everything is a remix) and go like "My game is Mario Kart meets Dungeon Keeper but with mature themes."* which is not so interesting as "one sentence".
For me theme is a deal breaker. Let's do a shooter. Nah. Let's do a cyberpunk shooter? Fuck yeah! Lot of people in gamedev think that setting is just something you pick after deciding what game you want to make. Like you decide to go for a walk and just need to grab hat or cap. No, you grab a fancy fedora and it's not just a walk it's a stroll down the Al Capone's Chicago ;) If we strip shooter games from themes there is almost no telling from one another. Setting adds flavor that speaks to people, that helps them identify with piece. Meet lots of people who tend to get obsessed with "game needs to have unique mechanic" or that just don't think that games could be about specific feeling/atmosphere. But it's another topic about games with no gameplay.