I think the spreadsheet metaphor is right but the spreadsheet UX/UIs has not aged well. Why Microsoft would do important changes into one of its cash cows and suffer a new wave of bugs and incompatibilities?
Big companies have all the money to modernize their systems yet they know the execution is difficult if not impossible to achieve in time. The classical story about running an older operating system and/or application that works instead on venturing on modernizing it.