WideBodiedEng,
That's a good point of course. But consider this hypothetical situation for a moment. Suppose you work for a company and you buy some shares in it. Soon after that the company, which is profitable, decides that in order to increase its profits it should reduce your pay.
Now you have a dilemma. If you strike to protect your pay the value of your shares might reduce. If, on the other hand, you allow your pay to be reduced without offering any resistance your income for the rest of your career will be threatened and the company will know that they are now free to do what they like to you. What would you do?
Note: before everybody rushes in to say that Aer Lingus has not threatened to reduce the pilots' pay, this is merely a hypothetical situation. Everybody, please feel free to say what you would do.