I believe this "more features = better" mindset is at the root of the misjudgment, and is also the reason why so many otherwise smart people are bad at product design (e.g. most open source projects). If a MacBook with OSX and no keyboard were really the right product, then Microsoft would have already succeeded with their tablet computer years ago. Copying the mistakes of a failed product isn't a great formula for success.
XWiki guys, let's prove this saying false ;-)
Actually, the last paragraph of the list applies to XWiki as well thus I'm not completely sure where this leaves us standing...
Disclaimer: This advice probably only applies to consumer products (ones where the purchaser is also the user -- this includes some business products). For markets that have purchasing processes with long lists of feature requirements, you should probably just crank out as many features as possible and not waste time on simplicity or usability.