It's not like you are an employee of any MSC and they are telling you to do the same work for less pay. As an independent contractor, you can pick and choose the jobs you enjoy doing. Don't like that the fee went down?....move on. Other companies will pay better, maybe or not.
If you think all ms'ing fees are too low, then find another profession if you don't like it. Hey, we all want a bunch of money - the msc's do as well. But, you are unlikely to be rolling in the dough in this profession. (I know, I know - some do QUITE well)
One of my most fave msc's had a sudden and abrupt ending to a ms program I had been involved with for over ten years. And, just like that, they lost the contract. It went to another msc where the pay was $ 1.00 less. So, the client just took the better of two bidders that time. Who wouldn't want to save money (I know I do).
Anyways, they may get less quality reports, and maybe they won't even be able to fill them all. I won't touch them (out of spite). But, that is how the industry works, generally.
Just my two cents.