The value of equity for a public company isn't a metric that only investors care about. It is the most comprehensive measure of a public company's well-being. It describes how much money the company is making and it predicts how much money the company is expected to make in the future.

E.g., suppose Facebook's equity takes a significant decline in value on the public market: employees become unhappy as the equity component of their compensation declines; Facebook's ability to make large acquisitions becomes more expenseive when its stock is worth less; and its ability to raise capital diminshes because it's more expensive to borrow exactly because their financials aren't as good, according to their stock price.

I personally believe that the long-term goals of investors and founders are very well-aligned. I believe that the common statment by founders nowadays, that they are building a company not for their investors but for their users, will produce the long-term financial results that investors want. It's the short-term goals of investors that conflict with that.

In short, equity isn't this isolated thing that can be happily ignored. It's tied to everything.