why to run Windows on Macs

Using Parallels Desktop for Mac or VMware Fusion it is quite easy to use Windows on an Intel based Mac. But why? Some applications seem to be so essential, that it makes sense to run them in the background of your Mac, even if they need Windows to function. Just some examples: ipdrum.com, Orb, ClipInc and of course these 12in1 SIM card products from Brando. Some import/export utilities for Outlook might be handy, too, if you want to transfer lots of data between PCs and mobile devices.