For me, they're pretty pointless. I only set them in my save of my Interior Decorator. The rest of the time if I start a new game, I don't even bother to set any. It's like everything else in TS4 .... the concept sounds great, the execution is always lacking.
When I first heard about the Likes/Dislikes my expectations were like this:
Likes: Cooking
Expected Action: Autonomously Cooks
Hates: Dancing
Expected Action: Doesn't Autonomously Dance to the radio or music unless told to dance
Likes: Gardening
Expected Action: Autonomously Cares for Plants and Gardens
Hates: Painting
Expected Action: Doesn't Autonomously start painting just because there's an easel
And so on ..... And so on.