"Today is the first day of the rest of your life" is an excellent adage for addictive personalities or people who have been through an upsetting experience. It's a horrible way for businesses to operate, though, and that's what many companies are doing.
To produce tomorrow's successful products, you must be aware of what has already succeeded and failed. Sure, times change. Tastes come and go. Fashion is fleeting. Just because an idea failed yesterday doesn't mean it will flop tomorrow. But unless you understand why the concept failed, odds are you'll make the same mistakes again.