That seems like a feature, not complexity? It's not like it made deploying MS word any harder to add the fax button.
Faxing isn't a great example, since from the perspective of most other features, it's probably just a special case of printing, but you can imagine it made it harder to build a web-based version of Word (what number are you faxing from? How does the computer in the MS data center contact or emulate it?)
It's almost always a better bet to add more complexity to your product to capture more market than to make it as simple as possible.