I'm not a designer at all, but as a player I honestly don't think that it blends in too much - Instead, it adds to the kind of "gloomy" feel of the room (Dark colors + not a 100% easy to discern some elements = Acts a bit like a dark room)
Not sure if I managed to say what I wanted to say, but you get me
Thanks! I've been worrying that the backgrounds might be too busy or blend too much with the more foreground tiles... been staring at these maps so long that I've become used to it, I think. I've tried dimming the backdrop even more, but I'm not sure that's really how I should be going about it. This might be a question I should ask in the forums.