The key to the product needs hierarchy is one that Walter only mentions tangentially: your product has to satisfy the needs at each level before moving on to the next. A product can’t be efficient if it isn’t functional. A product can’t be delightful if it isn’t efficient and functional.Delight comes last

It’s a great post by Matthew Ström, one of my favorite writers. I wrote about the same topic back in 2015 but didn’t address the above point at all.