Office isn't necessary, but it's by far the most popular "office suite", which is why most people do use it and why it's used in most businesses. Apple made their iWork suite specifically to have something for their platforms OS X/iOS. Even now their not updating Safari for PC.
I personally use OpenOffice on my desktop (win7), on my iPad I have pages/numbers, and on my MacBook I have Office:Mac 2011 (Home & Business). I use my Mac for writing documents for work, so it's nice to have complete compatibility as we have MSOffice on all the computers.
starcraft: "I and every PS3 fanboy alive are waiting for Versus more than FFXIII.
Me since the games were revealed, the fanboys since E3." 
Skeeuk: "playstation 3 is the ultimate in gaming acceleration"
