As an IT administrator at a large public university, I can say with absolute truthfulness that it is still the case that public [state] professionals are largely underpaid in comparison to their private-sector peers. As stated, we get great benefits, [usually] more holidays, and don't get laid off with little notice; that's the trade-off, and we know that going in.
However, we usually get annoyed when the agreed-upon terms of our employment are changed after the fact. Here in Florida, state employees were previously not required to contribute to their pensions; the current governor disagreed with this particular benefit and successfully pushed for this to be changed. At this point, we get back to the concept of promises; when I was hired, it was at a lower wage on the condition that the lower salary is offset by not contributing to my pension plan (among other things). If the government wants to save money by forcing contribution, that's fine so long as this new aspect of the terms of employment is enforced on new hires from the date this law was passed. This is not the case, and that's why the law is now being challenged in the Supreme Court.
Ultimately, it can be said that if people are so offended by this ex post facto law, they can find employment in the private sector and take a higher wage. I completely agree; while I hope the law is struck, it's not a "deal breaker" for me given the value I receive from other benefits that the state is choosing to still honor. Still, on principal, the terms of an agreement should be honored and not changed without due process, bargaining, etc., and that's what is at issue here.