Ooh, completely agree with this one. HUGE pet peeve of mine. I have an older iPad and there have been several instances where an app refuses to load until it's updated to the latest version. But then, when I try to do that, it tells me the new version of the app isn't compatible with my device!
As someone who has experience developing software, this really irks me because I know it isn't a technical limitation, it's purely a marketing decision. Apparently, the app makers and device makers feel like most people will just blithely spend several hundred dollars every few years to buy the latest and greatest tablets, even though the ones they currently have are still in perfectly good working order and are fully capable of doing nearly everything the new ones can. The app update/incompatibility scenario is completely artificial and, IMHO, a cynical and quite transparent ploy to nudge people into upgrading their expensive devices far more often than necessary.