All these "blueprints" just fill the bloodweb with more junk.
What's the incentive to use these? Like at all. I haven't seen a SINGLE one of them played and there's four of them.
I really don't care where the basement is. There's of course some maps where it's better for either side when it's in a specific spot, but I'd rather burn a map offering and get those maps with a 50/50 shot of it being in a good spot, than burn one of these and run the 1 in 50 odds of getting the maps where it matters at all.
As for the hatch, it also really doesn't matter. It would be completely broken to be a secret offering because then it's a major advantage, but being seen by everyone removes any benefit of using it at all.
So now on top of thicken/thin the fog, change hook spacing, +/- chests, and shrouds that never seem to work, we have even more utter junk clogging up the bloodweb which is already in a pretty horrendous spot.