I don't think it's an take advantage of situation. I'm not feeling sorry for WDW or CMs or anyone here. All I'm saying is that whenever a perk gets well known, and once it becomes something that people expect as normal, then WDW has to make an evaluation as to whether it's beneficial or not.
Here's my example: When I was in college I was editor of the school newspaper. I had my own office and everything, and one thing I did was keep a big flower vase filled with candy for people to come in and take when they felt like a sugar rush. Build a little morale, that kind of thing. But a few weeks in, candy started vanishing quickly and by the end of my second month, the candy jar would be empty every day. People were going in when I wasn't there and loading up. They weren't wrong or bad because they were just taking what I had offered. But after a while, when I'm going through a full bag of candy a day, I decided it wasn't worth it to keep refilling. When people asked me why, I kind of shrugged. Someone complained. I shrugged. The benefit I had offered actually became a thing people held against me a bit. That and my yelling
So to me, if too many people are getting into line later and later -- especially with the (until this year) escalating crowd levels -- and increasing CM time operating rides, then WDW will make a cost/benefit analysis. Even above, where welikeliza explained the CM situation, some department has an additional cost, and if that cost gets bigger than WDW wants it to be, they'll limit the cost somehow. We've all seen that happen in a lot of ways.