Perhaps it mostly still comes down to cost and reliability? Mainly in regards to storage media. Cameras are only very recently able to take advantage of low(ish) cost SSDs that are fast and of large capacity. In the recent past storage media was slow, low capacity, and expensive; or slow, high capacity, and really expensive. Couple that with the variance in card speed and card compatibility with different cameras, even with the same card brand. It's difficult to ensure a quality customer experience with these issues.
Also, you're an experienced DP, you may be more willing to work with difficult equipment (like a hacked Canon) to aquire a better image. I would venture to say that the majority of these cameras end up in the hands of jackoffs like me who participate in this as a hobby and don't have the inclination to dick around with a finicky camera.
RED caught a lot of shit for charging astronomical prices for their branded SSDs but it makes sense if you are quality assuring reliability and compatibility. I'm not sure how ARRI handles this aspect of their cameras but I'm sure it's much of the same. Limit the customer to what you're sure will work even though the cost is high. In these two cases you can do that, but with a consumer camera you will probably account for the lowest common denominator and accommodate accordingly. Democracy at it's finest.