OK, getting some mixed responses here...
As I say it's clearly a SOP so it's no mistake. I've assumed it's for collision avoidance but with all the other lights including the logo lights do we really need a focused beam of light aimed directly into the windscreens of your fellow pilots? To be honest now I'm ready for it I do remember to look away. It was more annoying the first time as I wasn't expecting the equivalent of a landing light shinning sideways. Would it be instant dismissal if one were to use a bit of situational awareness and maybe switch them off on occasions where they do more harm than good? Anyway with the procedure recommended by the regulators looks like I'll be seeing the other operators doing it soon too.