Game designers should always have the target audience in mind when designing a game. That is imperative. If it is a recreational video game, it is most important that the player has fun. Freedom to self-expression in designing a game is still a vital aspect, but most not conflict with the end player having fun.
Of course, if your target audience enjoys artistic expression, then by all means, express yourself artistically. If your target audience enjoys mindless shooting, then that’s what you should work with. This is not to say that all teenage boys enjoy shooting games, and thus designers should only design to that, but if your design is not to appeal to your target audience, then it won’t be fun, and thus you are failing at game design.
Design for your target audience to have fun, after all, a game isn’t a game without it’s “fun factor”.
