.TK let's people have a little more freedom when it comes to making sites. Instead of having to buy a dot address they can use .TK with any free webhost. So instead of forcing people to type a long link they can remember a short site-name.
Like instead of
http://www.geoshities.com/stareditNet/ it could be
http://www.stareditNet.tkMakes it easier to remember, faster to access, takes up less space. Basically it's a friendlier way of presenting your website and a way to look more professional for those who cannot afford webhosting and dot names.
It also allows people to have a site appear not affiliated with a website hosting it. Like say SEN hosts clan U's website and Clan U would move their forums to their site. They could use something like clanuuu.staredit.net or staredit.net/clanuuu or they could use their dotTk. I realize Clan U pretty much
is affiliated with SEN, this is just a hypothetical situation.