I had this thought about auto makers too. Does it really cost more to make soft pleasant plastic interiors than hard plastic? Or to make gear indicators for manual cars? I'm sure there are many factors, but part of it is perceived value and demand. By making things like a gear indicator standard, they increase the expectations of what you get for a certain amount of money.
Instead, they'd rather upsell you to a higher level model where you get those bells and whistles along with other options and pay a premium on the overall package, increasing their margins, even if they're using the same computer in all models. This is actually a fairly common business practice. Even computer CPU and RAM chips follow this model...
Bikes: 2008 Kawasaki Versys, 2009 Kawasaki Ninja 650R - RIP 1999 Suzuki Katana
Cars: 2004 Subaru Impreza WRX STi, 2007 Subaru Forester XTs