retirering googles after certain use seems like a great idea to me. As a rock and ice climber I have a ton of gear that has been retired. I will spend $300 on a rope and replace it after only 10-15 decent falls. If i drop a $25 caribeaner onto a rock even from 5 feet i will retire it to another use.
Safety is very important and as stated we only have 2 eyes. In general there are many injurys i have seen over the years playing airsoft but luckily eye damage has never been one of them.
I am very happy to see the majority of players being very safe when it comes to thier eyes.