freestyling isnt a nececity... and yes when freestyling ppl do spit written lines at times, freestyling is spittin summin off the top of your head.

ill usually make 4 lines in my head to get me goin, then continue from there.. every now n then spit a written line or couplet if my mind goes abit jus to help me get on track, n theres times its not intended.... but its expected when u freestyle.

but freestyling has its advantages, cos freestyle takes raw skill to do effectively, n it comes in handy for battles(which is another good way to get ur name heard), cyphers, feedin off what sum1 said previously or what sum1 is wearing or whatever, or where u are havin the cypher... if ppl see u bringin maaad skills with freestyles n they know it is cos of what ur sayin bein appropriate to there and then so it bein impossible to pre-write, people will be like "damn, if u can do that freestylin, i need to see what ur like when u write"