It would be good because the imformation provided would let you know if they are in fact new to the game of not and how much exposure they have had with SK. Example: here.
Sure you do have it in-game at "choose your knight" screen, but then no one player can view every created knights play history.
Forgot about that. Thanks! Although you can't click on other peoples names and see there's. Why am I interested? It's because it's really not okay with some other moderators of other forums to have a post of an introduction from a member who has been here for 2 year or more. It's considered spam in other forums. Just a warning.
What's wrong with warning people every now and then right?
For the same reason I stated here, publicly displaying a player's time in-game would possibly segregate forums users, wherein all the players' post would be discarded as the rants of a noob that doesn't know anything about the game. You don't need to have played the game for a long time to have a decent understanding on how the game works. All you need is a comprehensive mind that is able to think logically and able to adapt to new ideas.
This is already a feature. The only difference is that nobody could see if you're a new player or not. Click "forum preferences" beside the search bar and you should see your own time stamp. Also, I'm not sure why someone wants to know if someone is a new player or not.