As someone who has used the fanless 12" Retina MacBook, I can't put in words how nice of a feeling it is to have a fully silent computer. It's hard to understand why without actually experiencing it yourself, but it was a really big deal. If not for the awful keyboard ruining the experience, I wouldn't ever give it up.

It may sound (no pun intended) like an exaggeration, but I think more powerful computers going completely silent (fanless) will be the next most noticeable breakthrough since we got Retina displays on computers in 2012.