Seniors' discounts wouldn't create this slippery slope that you point out because it's already there.
Going back to my original question, where do you drawn the line then? 70? 60? 50? 40? Nothing will make everyone happy!!! Then we will have CM's checking ID's, then we will start seeing threads on how to get around those mean CM's who enforce the rules! Maybe we can make up make up fake ID's!!! Don't put it past people -- look how people try to get around room occupancy rules or how their 12 year old should really be getting a child's ticket, etc.
Quite simply, WDW is a luxury product and either you can afford it or you can't. What's next? Senior discounts for Lexus buyers?? Front of the line pass because you are "old"???

But I think this thread has drifted off the OP's question and can probably be closed!!!