I see a couple possible reasons why they were turned off
1) Bandwidth friendly. To speed forums up.
However, since all the pictures are hosted elsewhere, this isn't directly related to the forum server's bandwidth. If one is worried about dialup users, they can go into their options and turn images off by default and put it in the state it is right now (Showing a link)
2) Questionable content. To avoid people posting porn and what not.
I haven't seen a single one of these posts, it's mostly people sharing screenshots. The added fact that there are eight bajillion admins to regulate it...
I would like images back please, if for nothing more than for the editing sections, so people can post pictures of their skins, levels, etc