Ubisoft have confirmed they are seriously considering removing the 2 second window Defenders have to jump out of buildings before being spotted.
Brand Director Alexandre Remy said “We’d like to see some changes to the timer for defenders leaving the building, mainly because of defenders that run outside to spawn kill at the start of the round. It’s tough, this one.”
It's one of the challenges of making a game that if they make a change and get it wrong they will seriously get some community backlash. I personally love the idea. I've had my fair share of good kills when I can jump out and nick a kill but I have to admit it's one of the worst feelings getting spawn killed and/or getting killed by a Defender that is outside the perimeter and you didn't spot where they were.
I think they will eventually change to a zero timer after tests. If youu're going to change from 2 seconds, you might as well remove it rather than leaving any specific time unidentified.