Looking over the list, I recognise a few of the recent releases, so I wouldn't describe the list as being in bad shape. I'm not sure what you mean by 'outdated material' - for the most part texture mods don't really become redundant. As for the dead links, I'd say the starting point would be trying to contact the creator and see if they can reupload. After that, make a list and see if anyone has a copy, then upload yourself (with the creators permission, if possible). I don't think clearing out the dead link entries should be done without at least trying to find the content. Approaching this from the other direction, is there anything you were expecting to see but didn't? If there are texture release threads you know of here or elsewhere that aren't coordinated with the wiki you can let the creator know. It's a wiki so you've got as much power to update the list as the rest of us.
On second inspection, there are actually many more dead links than are indicated. Trying to track some of this stuff down sooner rather than later would be good.