Sometimes when I start a thread, I am interested in the replies. And when the board is busy, it can be a very hard task to find the thread I just posted without noko. On a slow board the thread will be right at the top of course, but I might still want to bookmark it to check for replies later.
"Noko" is also tremendously useful when chatting with someone in a thread. Of course imageboards should not be used for chat, but not even text boards like Kareha or Shiichan support it.
On a slow board it doesn't matter but I'm looking for a script for a board I hope will be popular.