[whyoh]

>HP cartridges including the printheads will take a lot of complexity away from the open design.

Yes, but it also means it won't be cheaper or more reliable than a regular printer. The print head is what fails most often and you'll still have to buy a new one.

[dymk]

Aftermarket ink cartridges that are HP compatible are quite cheap compared to brand name

[whyoh]

Those are made from used HP cartridges, so they have a shorter life span.