In my opinion, bumping isn't bad if you're a member who's new to the forum atmosphere and doesn't know how things run.
I for one started out on the forums bumping every cool build in the gallery I could find just so that I could express my opinion. I didn't know that it was wrong, and I didn't realize that the forums are a working chat log, being updated and replied to every few seconds. I just assumed it was a place someone could stamp their opinion in a thread just so that others could see. I learned later on, and here I am now.
On the other hand, if you're an experienced member who's been on the forums for some time and you go on a bumping spree... that's punishable.