I have a lot of disorganized thoughts on this issue. Please bear with me as I try to gather them together.
For the sake of exposition, let's say Mayer makes some $$MM/y, the exact number isn't really important to my point past a certain level, which she most certainly is.
What is she being paid that amount for? Let's explore each of the obvious options I see, and an expected common reaction (Had written logical, but that's not what I meant, since many common reactions are far from logical).
- To restore the company.
This clearly did not happen, if this was her job, she failed at it, and for most "normal people", getting paid that $$MM/y seems very off compared to what we might receive in such a failure.
- To as you say, preside over the decline. (age gracefully)
The argument I'll pose for the anti-Mayer sentiment in this case can be applied more broadly, but is most fitting here. One might expect this sort of role, in parity with firings, would include policies of waist tightening at all levels. I'm not even making a stance for or against these things in this argument, but the press about a slew of very exorbitant and very material benefits when paired beside firing of boots on the ground (again, not taking a stance, just observing the contrasting sentiments) give the _PERCEPTION_ of "let them eat cake", to put it glibly.
- To as you say as well earlier, be a face for the markets.
If we chose this explanation, realize the "figurehead effect" is a two way street. A famous CEO makes markets look positively on the company (is the thesis) regardless of the company, so if a company is doing badly, should not that emphasis also be on the CEO? It seems disingenuous that the CEO gets the credit for success but not for failure. I'm not saying this is logical, but it is consistent to placing significant value on a figurehead.
This last argument is the weakest, given that the markets probably take into account perceived CEO skills as part of "figurehead" status, but the BROADER market (sentiment of the people) likely can't inspect that deeply. So if the financial market loves kingmaking, the people get to see a king, and have their own expectations which do go both ways (in terms of lionizing success c.f. elon musk, and demonizing failure)
At the end of the day, each of these universes results in a very negative sentiment towards Mayer, thus my not being as surprised at that outcome.