While I'm sad to see any ride go, I'm sure there are very good reasons like maintenance costs that are causing the decision to remove any ride.
I just keep reminding myself it's like buying a car. At some point you have to make a decision...do you spend more money on it than it's worth or do you cut your losses? For example, my car is only 5 years old, but it has almost 150,000 miles on it. I know I have to spend some money on it soon for a new clutch, suspension, and tires. If I spend those thousands of dollars to keep it running, what happens when the engine goes or it gets totaled in an accident after that? Eventually I'd end up spending as much money as it would cost to buy a new car.
A perfect example was Chiller. Think of how much they spent trying to get it up and running and it never paid off. Just when one problem was fixed, another one sprang up.
When we're talking about rides that are so old either the manufacturer has stopped making them or is out of business, getting replacement parts is difficult if not impossible. Having custom replacement part manufactured costs a FORTUNE.
A friend of mine used to work in a precision machine shop that fabricated replacement ride parts among other things, as they would charge tens of thousands of dollars to fabricate a part to the exacting tolerances required for rides.
I'm sure the company would LOVE to just buy replacement rides to fill holes where these rides are being removed, but they don't have the money to do it right now. Couple with that longer lines mean more revenue from Flashpass and fewer rides mean reduced staff or better staffing for the remaining rides and there is a silver lining for the business. Also, if sacrificing a couple of flats mean that other rides are saved (like the Skyride) it may be a worthwhile sacrifice.