Hmmm. I was going by the fact that they seamed EXTREMELY sturdy when the mutated Worf was trying to get through them in "Genesis" to retrieve Troi. Even the crew cabin sized Holodeck doors in "First Contact" had to be pried open by the Borg in as opposed to being easily knocked down by them. Maybe the sickbay and Holodeck doors are sturdier than the ones in the rest of the ship, although, I would find it hard to believe that Flag Officers would be housed in quarters with "flimsy doors", but who knows? Stranger things than that have happened in Star Trek before (including the aforementioned "Genesis" episode).