I use Omnifocus used to put target dates for the "important" things because I wanted them to stay top-of-the-list and not get mixed in with 100 other things. Then like you I would find myself modifying that date on "overdue" actions to move them into the future. They weren't really overdue...I just hadn't made the arbitrary date I had assigned. I've changed this by taking advantage of the "flag" functionality, which lets me mark something as important without setting an arbitrary due date. It saves me the time and deflation of going back to adjust due dates. And I can still scan all of my flagged items when it is time to reflect & engage.