Well in this case the jumps were as much planned as they were accidental. I could have placed that staircase 64units (the distance of 2 stairsteps) towards the middle area with the pillars but then there wouldn't have been anything to jump. And the wall lights would probably have looked sexier if I built them into the walls but again, then there wouldn't have been any shortcut jumps to the Yellow armor. If you like your map to offer some trick jumps you can of course always design them on purpose, making use of the doublejump physics of Q2. As long as you make brushes (especially stairs) sticking out here and there and don't make everything flush with the walls and floors then people will always find opportunities for jumps.
This 2011 article by n00k!e is definitely a must read, albeit it's written from a jumper's POV, not a mapper's. But certainly if I ever attempt to do my own research into this problem it will be listed in bibliography section. ;-)