You have to grasp a rotary switch and turn it (less so for rotary encoders with large knobs). A protruding side switch is a lot easier to accidentally activate - adjust the PSU, go to frob whatever equipment's to the right of it on the bench, and zap. On most test equipment, hitting something by accident is an inconvenience at worst - on the thing that's powering your logic, you really want more, not less, protection from fumbles.
I speak from bitter experience. Also, when the BBC went from rotary mixing pots to linears on its desks, it made them fade down when you pushed them up - so that if you caught them on the cuff of your jacket when you were reaching up for the controls above them, you'd fade to silence at worse, rather than fading up something to be accidentally broadcast.