I don't agree. I don't deny there have been plenty who abuse H & S legislation for their own ends but wearing glasses from an early age, combined with snowballs, is a recipe for disaster.
A lot of kids aim specifically for the face. If you wear glasses, that can be mighty dangerous. And taking off your specs so you can join in conveniently ignores two facts: a lot of kids wouldn't have anywhere safe to put their specs and - the most important, perhaps - once they've removed them, they aren't able to see well enough either to dodge incoming missiles or to fight back.
So, no; restricting snowball fighting to specific areas is the answer, but a lot of kids don't enjoy snowballing, in the same way a lot of kids don't enjoy football. Often, interestingly for the same reasons.