I agree that for most mundane tasks that people do (email, web-surfing, word processing, light gaming), they should be indifferent between a windows or mac laptop (heck, you can even do these on a phone or tablet).
However, find me a windows laptop that lets me use icloud, photostream, imessage, access itunes/app store, install existing mac software for free, comes installed with ilife, boasts airplay-mirroring, has a liberal 14-day return policy and excellent after-sales support (these are just a few which come to mind at the moment).
These services cost Apple money to maintain, which is reflected in their higher hardware prices. If you already own a plethora of mac devices and want them all to play nice with one another, than to me, another apple device is really your only option.