Charceter sheets should be seen as what they are. The starting point.

They allow you to make sense of things, list your information and details, and also to allow you a refrence detail so everyone can see who is who, what and so without countless questions. 

Now, are they your plan, future or Role play, no. 

The charceter should go with the flow of things, and within reason that's going to change, and the CS is merely the starting line. It can show a idea where it going to go but we all seen RP where the idea takw a path of its own. 

Important for many reasons, this just a sample. 
But... They should not be all, end all for that charecter.