Sound quality is certainly a big part of the problem, but I also find the skills of composition and arrangement lacking in many releases. I tend to hear a lot of these tracks that just knock out aggressive beats in near-random sequences with crazy noises all over top (Cosmo and Highko have taken this to an absurd extreme). How many producers bother to set a mood, build a story, or inject their creations with any kind of artful purpose? A lot of it is just attitude and posture... bad-ass project names and evil song titles, scary samples, extreme BPMs, a competitive harder-than-thou ideology. Darkpsy is like the punk rock of psytrance!
Again, I feel as if I should state I really enjoy the dark side. I could go on and on about the merits of Ghreg on Earth for example. Now there's an intelligent artist with a sense of purpose! All these kids releasing killer filler on compilations simply can't compare.
Lastly, saying that most darkpsy releases are better than most full-on releases really isn't saying much at all