Logo designs need to be flexible, in the sense that you can keep adding and innovating the same concept to refresh the logo over the years without confusing loyal customers with a different design altogether. Take Adidas, for example. It uses the same idea of three parallel bars while making minimal visual changes to the logo to refresh the brand in the minds of new and existing customers.
It is all about keeping the logo relevant in years to come. You never know what the future holds for a particular brand. In an age of constant changes as far as media and devices are concerned, a logo design that is truly timeless is worth more than millions.