I've worked in tech for 30 years and never experienced a single company that does math the way you describe: "I.T. generates or saves us $X million per year therefore we'll share that with frontline developers." Ha, puhleez.
In my experience, you'd consider yourself lucky to work for a company that sees I.T. as a strategic/operational advantage (and not merely a "cost center") and therefore pays its staff 10% better than market average plus bonuses.
Unfortunately, I've worked for truly "I.T. forward" companies like that and still seen a merger or buyout completely flip the culture. Overnight I.T. salaries and budgets were seen as indulgences and people were laid off or quit in droves.
The one thing I've learned about this industry is that no matter how innovative or adept an engineering department is, an exuberantly stupid executive team can completely squander and destroy that asset surprisingly quickly.
Do you think they would sooner cut off their nose to spite their face?