What core mechanic is such a poor fit? Are there any standard remediations (choice of feats, items, or class features) that fix these mechanics, besides "Play a hunter?"
From a purely subjective-memory point of view, I didn't feel that they performed very well as a controller. It didn't (this was 3 years ago?) feel like they could clear minions, cause people not to go places, or move people around particularly well. Contrast invoker: fear my minion clearing and status wrath; wizard: fear the fact that I'm a wizard and can do anything I want; psion: fear my debuffs; etc. There just wasn't anything for enemies to fear about the seeker.