...is to turn the question around. There are two electrical generation utilities connected by a wire: your solar panels and their big fossil plant. Their problem is that they are *required* to buy power from yours when yours happens to be generating, whether they need any power or not. They *have* to turn down or shut off their big plant whenever your system feels like doing some output.
How would most of us feel about being *required* to buy electrical power whenever their plant is underutilized and needing some extra work? Plus, they can build it up all they want and thus make you buy more?
It all imposes costs and they're attempting to recover them. That said, all profit-making utilities love to exaggerate their costs to regulators so as to be allowed higher income, all such claims need to be checked, and the budget for the checking - and the internal information made available to the checkers - needs to be as much as the utility had for the request to the regulator.
With that caveat, there's nothing wrong with this; the system imposes a cost, they deserve compensation. Any contrary view is really based on a belief that solar power people are inherently "good" and the utility is inherently "bad" by using fossil fuels and thus deserve to be punished for their sins.