Because STF was made to give new players an option to make insta lvl 30 character for strategus or something like that. You can only imagine the possibilities if some faction has only STF characters and they change the build to be fitting in any battle they are attending. That is why it is one week, just like old retiring system before the big January patch. I don't know if it is still possible to have skip the fun character as main, but they can't use the marketplace.
I was one of many who were suggesting and supporting this cooldown time for STF, but at the time it was clear that those characters would also be in strategus too.
Maybe it could be made this way:
- If you make Skip The Fun- character as your main for strategus, you have to wait for a week before you can have another STF main.
- If you make Skip The Fun- character as your ALT, you could do another one whenever you want (it could be annoying to watch one guy changing his character build every time he joins the server, but he has to grind some gold before he can have effective gear because he has only 10k)