To keep glass off the track in the event of a crash.
Actually we were required to either tape over the mirrors or remove them. The reason is so that you are focused on what's ahead of you, not worried about what's behind you.
Wow, that is one beautiful track, what views, almost distracting from the focus of the race-line...
Sure looks like you had a great time. I've often thought about taking mine out for a day like this, but the bike is simply too expensive, for how fast I ride (when on my other bike)... (defer to my YouTube channel and you'll understand) =)
Dave is correct, the tape on the mirrors / turn signals / brake lights (which I noticed some did not have, and is alright in this big-bike scenario, but in a Sport bike session, that's a huge No-No!), is to prevent any sharp shards of plastic or glass coming off the bike, in the event of it going down, and thus to prevent other bikes running over those pieces and rupturing the tires, causing a more dangerous riding situation.
Breezly is also correct, that it allows the rider to more-focus their attention on riding, and what's ahead. On the track, the rule is, "who's ever front wheel is ahead, has the right-of-way".
Have been doing track days and racing for six years now, I've just about put as many miles there, as on the street (not really, but it feels like, add up the MPH, and I sure have equaled the track to the street) =) ...
First day on the forum, and first post. Sure glad to find some riders who really like to get out there and have some fun on their Wing's!!!