If you only do things that you want to do, you'll stay the same as you are now. You're not as likely to see growth- in performance, in looks, in functionality. One of my favorite quotes is "If it doesn't challenge you, it doesn't change you." To change your body, to improve your fitness, and even to be successful in life, you must learn to do things you don't want to do, simply because it's good for you, and because doing them will help you reach your goals.
That being said, when I come into the gym and see Deadlifts on the board, part of me wants to just run back to the car and take off. Not only do I suck at them, I just hate doing them. They hurt my back. I always get emotional during Deadlift wods, and I have to work really hard to push through that mental block. Every time.
Here's the thing: it would be really easy to cut down my weight, or cut down my reps, or (since I usually know the wods ahead of time) simply take my rest days on deadlift days. But that's not what this is about. CrossFit is about confronting your workout HEAD ON with discipline, determination, and guts. It's about finishing the workout even if it takes you longer than you wanted it to. It's about doing what's on the board because you know it will make you better.