I think many product designers try to replicate the success of printer cartridges. I try to avoid buying any device that limits the input or supply especially those that require a cartridge.

It's a clear method to milk consumers and they can hardly justify the benefit in most cases.

I even don't buy the idea of capsule coffee machines. I like those that give you the option to use pads, but not those that only accept capsule. The environment impact is one reason, but I also want the freedom of choosing the supply and the having control on the running cost.