Other headaches of new design includes a lack of compatibility with many accessories. In the near 10 years iPhone has been out, Apple has only offered the 30-pin adaptor and now Lightning yet that didn’t stop people from freaking out. Imagine if each phone each year had a different design. Goodbye to using your previous case or dock, or center arm rest in your car that supports certain designed phones.
With Apple being conservative about when they shift their design, they allow for a far healthier ecosystem. I see accessory makers all the time opt not to support Android (Samsung) because by the time their molding design has been paid for and is in production, a new model comes out, making their old molds obsolete which is extremely expensive for small companies.