The screen was not properly designed... A smaller screen does not affect the vapor. Right after your use it nothing falls through, but small particles can add up over time. I use my herbalaire a lot, and if that screen wasn't there I'm sure I would have duff dust down in there. Also so many pistils go right past the top screen and get suck to the resin in the tube or go up into the bag. And you said the air flow keeps the bud up, do you not turn the pump off when pulling a bag off? Do as you will, I try to take the utmost care with my things. Your not going to break it with out the screen, I just want my heating element to be as clean as possible for years to come, and you can't get in there to clean what ever fell in out. A screen on the bottom of the bowl is only helping, especially when those days your down to shake.