The answer is pretty simple actually – shorter is better in urban combat and self defense.
The Israeli Military has been headlong in their pursuit of bullpup weapon platforms based on solid research and years of field testing in the battle scarred Middle East. What they found was that shorter weapon systems are far more advantageous in the confines of urban or suburban conflicts – in other words, they are easier to use effectively in places like your home where tight corners, smaller rooms and other confines make a longer weapon harder to deal with.
The Israelis also found that bullpup designs were able to maintain a barrel length that didn’t affect the accuracy or performance of the weapon. Because of the design of a bullpup system, the barrel may be maintained at optimal length, and the components are moved back, the stock shortened and the over all performance greatly increased.