So I finally got to the rank with my Gorn character to play the Fek'lhri missions, which I wasn't exactly anticipating much because when they came out, the reaction on the forums was, by and large, "OMG if I wanted to play this crap I'd play WoW."
However, I'm completely befuddled by this now because I've beaten the arc and I have to say the Fek'lhri missions were some of the best I'd played in this game for story, entertainment, and sheer combat ... they distinctly felt like I was playing a really fleshed out Featured Episode series, and when I was done I truly felt like I had played something more epic than most of the Fed missions in the game.
I'm bothered that this approach was abandoned. It was a big part of the Season when it came out, but the STO team has focused on neutral-themed Feature Episodes for the bang-for-your-buck factor. As useful as that is, there is still ... and always will be ... a feeling that the Klingon faction is lacking in content as long as Klingon specific PVE content isn't there. To me, the Fek'lhri arc proves that they know how to do this -- all they need to do is do an arc for, say, the Gorn, the Orions, the Nausicaans, and the Letheans ... and place each arc at each tier, and I'd consider Klingon PVE content done. I think its entirely possible for them to handle such as Featured Episodes too, if they really wanted to.
Obviously that'd be resource intensive, but the pay off for having people no longer complaining about Klingon content would be worth it.