This is one of those discussions that goes round and round and round again... I never usually post in one but here goes...
Not saying I do one or the other, just playing out the opposite side here...
When you are loading a vehicle, are you usually standing there perfectly silent, listening to every word the CM says, or are you talking with your family, tending to your child, etc? Probably the latter, most folks are involved in their own conversations and have no clue that the CM is saying anything to them. Especially if you are in a large group, you might be talking about where you are going to eat next, or what ride you want to get on, or you might be calling the rest of your family on the cell phone to find out where they are, and when to meet up. OK, lots of distractions, people can and do easily miss the announcements made by CM's.
Think back to your first trip, if you had not used the disboards - our first trip was in the 80's when there wasn't even internet - and you were unaware of the "rules" regarding flash photography, so you want to make a good photo album of everything you did. Now you have some person in your face yelling about no flash photography - in my mind I would think, hey, your not a CM, your just some guy on vacation, why are you trying to boss me around??
If people are unaware of the rules, how can you blame them for doing something?? I have heard so many people on rides get beligerent at others regarding the no flash photography thing, that the people taking the pics first become defensive, and then defiant.
So, IMHO, if the flash photo thing bothers you, please talk nicely to the person doing it. I really hope the water gun thing on here was a joke, because squirting someone in the face with a water gun is FAR MORE rude than a few flash picures, for real.
And please remember too, that you may have the luxury of going back to WDW year after year after year. Try to remember, the people taking the flash pictures, it may be the only time in their entire life that they may get to WDW.
Is a few flashes in my eyes going to ruin my trip? No way! I'm on vacation, nothing can bother me that much!