Well, "Hordes Of Chaos" did have a lot of melody but that doesn't mean it wasn't good. Just cause it was different in that aspect doesn't mean it was a step back for them. In fact, songs like "Demon Prince" or "Escalation" are probably Thrashier then a lot of material on the last two albums (at least in my opinion). I think the band is pulling all the lessons they have learned together remarkably well whether its the Gothic tendencies from their brave albums or the more Groove orientation from "Enemy Of God" I think the band is making an even more unique sound for themselves then they had before.
Perhaps I just love Kreator
It is obvious that the band is trying to find a "new" sound, but "unique" will be very difficult nowadays (the most "unique" thing I've found lately was Cynic's "Traced in Air" -which I really loved-), and even more difficult when talking about a Thrash Metal band.
But well, it's OK, I agree with bands that try to make some experimentation with sound (for Hell's sake, I like "St Anger") or structures, specially when everyone is expecting the opposite. The paradigm of constant change and (some) experimentation with success might be Judas Priest, constantly reinventing their sound without losing their way.
If Kreator is trying to "find a new sound", I think that this would be Kreator's "Point of Entry" (continuing with the Priest analogy)...but that's just your point. I can't see any taken risks in "Hordes of Chaos". It's just an "I feel comfortable with this sound, we've been succesful, so let's take the essence of our last two albums (maybe som outtakes too) and make a 'potpourri' of it but recording it like we did in the beginning".
What do you get by doing this? A beautiful promotion: "Kreator has mixed the sound of their last succesful albums but without losing their roots. Oh, yeah, Kreator back to the origins!"
...bollocks! The only connection I find between "Hordes..." and "Pleasure To Kill" is the name of the band, but this ain't the problem -again, I like experimentation. The problem here is the feeling of comfort that attacked Petrozza & Co's brain during composition of this album.