IBM/Lenovo probably designed/modeled their notebook mouse trackpoints after nipples such as those. Then again, the downside is users may try to either suck the trackpoint/keyboard or there might be difficulty in being able to close the lid/screen because of a clearance issue ? I can imagine that as what was going thru the engineers thought process when designing the trackpoint. He probably looked at the keyboard and thought, "what's missing here ?", "I know a plump red nipple in the middle of this keyboard !" He then took the idea to the boardroom and obviously the rest is history, there wasn't an executive that voted against the nipple on the keyboard. Test users spent hours using the nipples and even if it wasn't a touchpad, it was more fun.