Simply put, it's the age-old question of "Why do they always jump in so far from the node?"
Well, if it were a Knossos, the answer has already been provided by the Psamtik.
If it were a normal node, however, it's probably done for safety reasons. Canon has established that jump drives need to recharge, so if a warship jumped out of subspace and directly into a node, it has to wait for quite a while in order for its jump drives to recharge, during which it would be slightly more vulnerable to being disabled or whatever, because any warheads aimed at its subsystems or turrets will hit home if the warship's point defences are inadequate. If it moves, however, the chances of a warhead knocking out a subsystem or turret is slightly lower, because most warheads take a lag-based approach rather than a lead-based one.
There's also the matter of a jump node being used often. If you have a warship sitting inside a jump node waiting for its drives to recharge, and a Hippocrates jumps in, it can't use the node because the warship has parked itself in it.
And then there are traffic issues as well. Imagine if a ship is waiting for its jump drives to recharge at a node, and you have twenty other ships waiting for it to recharge, with a few more ships jumping in near the node every minute. The jump node will experience a bottleneck.