The moniter can go higher than the invisable roof. If you tele yourself into the rafters and go forge under a Ceiling support beam, you can has moniter in the rafters
Adding actual scenery. And I don't mean barrels. I'm sick of tired of making all of my maps seem like it has a warehouse feel to it because I use scenery like road blocks, barrels, forklifts and crates. I want to be able to play grass, dirt or whatever. Seriously, throw me a bone here Bungie. I'm pretty sure a little addition of a 12x12 grass wouldn't be that bad. It's better than looking at a wall as a floor. So I can at least cover the floor with grass. :-/
Color change on objects would be nice because nothing matches and always looks like a pile of neatly organised crap.
every object is possible for every map with more cash and higher item limits for each object so instead of 16 walls you can use 32 walls. which will allow you to do more things
carbine placement on maps and the ability to add simple triggers.(player A goes into hill 1 item spawns) I think a lot of cool stuff could be done with triggers. (traps, swithes)
I agree, it's like Bungie tried to make it hard as possible to make stuff on Foundry. I think it'd be awesome to have an option to turn invisible walls/death barriers off in Forge and Custom games. Why not?
Or... Scarabs on Sand Trap since the Elephant is probably the most ineffective vehicle in the game. Seriously, it would be so much cooler if the crane on it was a big gun tank gun.