There is no real need to have the trust ratings displayed in the bitcoin discussion and similar sections because no commerce takes place there. Since you do not conduct business there there is no reason to need to know that someone is a scammer and pointing out that fact will only lead to distractions to conversations.
@Muhammed Zakir I'm not against having it always visible, but I don't know if it is very important on all boards lol.
How is trust important on off topic or politics and society for example?
Negative trust feedback aren't left only for scamming. Example :
https://bitcointalk.org/index.php?action=trust;u=159191. This negative trust will be useful in Bitcoin Discussion.
-MZ