UA made the operational change for the greater good..they did the right thing. However at the same time someone expecting a certain advertised product and is given an inferior product instead has good reason to complain and request compensation. I agree with the OP and if it had happened to me, even though I understand why they did it, I would have complained.

In fact I already did complain on behalf of someone I know who this happened to at SFO 2 days ago... awaiting the email response. She went from NC to E+.